Plaster has been decorated with paint since its earliest known usage back in 7500 B.C. Jordan. The rather simple mixture of lime powder, crushed limestone and water was used to achieve smooth walls for interior wall decoration. Ancient Egyptian builders employed calcined (heated) gypsum into their plaster, which improved the functional use. The duel use of form and function is evidenced by their opulent palaces and tombs, including the pyramids of Giza. The term “Plaster of Paris” originates from 15th century Montmartre, France – the source for its prized hemihydrated calcium sulfate. Of course other sources are now known, but this specific vein of gypsum was proven to be an extremely important component for mold-making and casting and the name is now synonymous with plaster. Traditionally shellac is used as a plaster sealer, but this article focuses on using waterborne acrylics for both sealing and painting.
Before painting plaster, it is important to allow the material to become fully dry. This process may take up to a month, so follow the plaster manufacturer’s recommendations on curing time. Ultimately, the plaster needs to be very dry in order for the initial priming layers to properly bond to the plaster surface. Drying rooms or low temperature ovens expedite the drying rate for objects.
Acrylics are alkaline in the wet state and adhere well to plaster. However, the surface of cast plaster is usually smooth and thicker paints often cannot penetrate deep enough to create a strong bond. Therefore, thin products are better suited as the initial coats. Uncoated plaster is extremely absorbent and allows thin products to penetrate deeply and seal the surface, thus paving the way for the next layer. This is the key to painting with acrylics onto plaster. Allow time for each layer to sufficiently dry. An indicator of this is the plaster darkens while wet, and then lightens as it dries. As each coat continues sealing the surface, the plaster remains a bit darker . Once the surface is sealed, thicker products such as Fluid Acrylics or Heavy Body Acrylics can be used.
GOLDEN High Flow Acrylics may be applied directly to unsealed plaster. These paints readily absorb into the plaster. The negative side effect is akin to staining raw wood; the color tends to be somewhat blotchy and uneven.
Woodworkers remedy this with a pre-stain conditioner. A ready to use, suitable conditioner for plaster is GOLDEN Airbrush Transparent Extender. This thin acrylic medium is applied directly to the plaster surface. Two or more coats create a less absorbent and more uniform paint layer. Certainly other products may be used (GAC 800 is an excellent coating for chalky surfaces), provided they are sufficiently thin enough to readily absorb into the plaster. High Flow Acrylics were compared to Fluid Acrylics on bare plaster and both absorbed readily with excellent adhesion. These paints are thin enough to not cover up casting details. GOLDEN Heavy Body Acrylics can be used on a properly sealed surface, but they will retain more brush and tool marks.
Acrylic paint may also be added into the plaster slurry to tint the cast object. This is a useful coloring method because, unlike surface painted plaster, chipped areas will not be as noticeable. Adding acrylic paints or medium may also improve the overall plaster strength because they form a network within the plaster. The concept of adding acrylic to strengthen plaster is not a new idea. GOLDEN Custom Product “Acrylic Modifier for Plaster” was developed around 1990 to improve the overall strength and chip-resistance of cast objects by integrating a matrix of acrylic polymers within the cast object. The liquid additive is mixed with water prior to adding the powdered plaster, usually between 3-10% of the weight of plaster used. At a 10% level, our limited testing revealed that the Acrylic Modifier for Plaster increases the amount of force required to break ordinary Plaster of Paris by 50% and increases the amount of force required to break USG’s Hydrostone by 25% . Hydrostone is a stronger and more durable plaster to begin with, so this increase is noteworthy. Adding acrylic into the plaster also reduces absorbency, thereby reducing the number of sealing coats required prior to painting. However, acrylic additions will also slow the curing time down, which can be an issue for some applications.
Once the plaster objects have been painted, they may be top-coated with a variety of materials, including GOLDEN Polymer Varnish, MSA Varnish or Archival Spray Varnish for decorative and artistic needs. Commercial topcoats should be used for more demanding functional requirements. Exterior use demands the use of waterproof coatings such as two-part automotive urethanes.
As always, if you have any questions about this application, please contact the Material Specialists in our Technical Support Department.
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Excellent article! I’m now surprisingly (well not too) inclined to begin work on plaster. I’m thinking of plaster sheets formed by pouring a 1/2 inch or so in a rectangular mold. The increase in strength may make this a practical idea—time and experience will tell. I’ll start small and work up and at some point add plastic screening at a mid point or perhaps sculpture grade plaster bandaging. Many possibilities come to mind, even polychrome sculpture beyond bas-relief.
Thanks for the great information! I have another question: Can I apply GOLDEN Polymer Varnish, MSA Varnish or Archival Spray Varnish directly to plaster as sealant if the plaster is not primed or painted first? Thank you!
Hello Yamin,
Thank you for contacting us with your questions. The varnishes may be applied directly, but they will readily absorb into the plaster surface. With gloss products this isn’t a big concern because they help seal the surface for subsequent coats, but satin and matte varnishes absorb in but leave the matting solids on the surface. In turn, this creates a frosted appearance (as seen in this video: https://www.youtube.com/watch?v=4hvobUjgPdQ ). On unpainted plaster you may not notice it, but it can obscure colors a bit. ALso realize that absorbed varnish layers are not removable.
My painting on canvas is done with pencil ,acrylics and water colour pencil ..how do I seal the work?
Hello Alka.
Test first, but I would suggest light coats of Archival Varnish. Start with Gloss, then once the surface is sealed, apply layers of the desired sheen.
– Mike
Hugh, that last idea sounds cool.
Thanks for the article Michael. I gave my flat surface plaster piece a light spray of varnish and did image transfer on it with a medium but it rubbed off more than another method I’d tried.
Great article!
I want to join two fairly large hemispheres (40cm) together and am considering a sealant to seal the plaster before I apply any resins. Is my reasoning sound or am I missing a step?
Thank you Daniel.
I have never tried to join two casts together but it seems as if it might be better to not pre-seal the pieces to better allow the resin to penetrate into the plaster. I think it would be wise to do a test to see which method has better adhesion using “strips” of cast plaster that resemble the rim edges. What type of sealant are you investigating?
– Mike Townsend
I was wondering what kind of outcome I would have if I mixed plaster of paris with the paint and layered it like one would with oil paint; for a textured look on a wood panel. What are your thoughts?
Hello Aubreigh,
Thank you for your comments. I do not forsee any issues with what you are describing, but I would greatly suggest making test panels to assure you have proper adhesion between layers and there are no signs of cracking in the dried applications. – Mike Townsend
Hi, I have a large (what I think is plaster) elephant statue that was once a coffee table(but just sat stored in the basement, painted an ugly green colour) well, I painted it with acrylic paint (gray colours to look more natural) and I want to put outside in my garden for summer weather, bring it in during winter months (I live in London, Ontario Canada). Now my question is “what would be the best type of sealant to use?”…..thanks for your time
Hello Dawn,
Thank you for your questions. I do not know how well it will hold up in an exterior setting even with a topcoat. Plaster degrades quite quickly when exposed to moisture and if it’s acid rain like we have here in the north (we are in upstate New York) the plaster might also dissolve quicker.
We’d advise against trying to place this figure – made with unknown materials – out into an exterior environment.
– Mike
I just repaired a small figure with a mixture of plaster of Paris and joint compound. I have done necessary sanding and painted with acrylic craft paint to match original finish. The finish on the piece is a satin finish. It will be stored and used inside. Any suggestion on what to use to seal newly painted areas? Thanks so much for your help.
Hi Linda.
Thank you for contacting us with your questions.
The first thing I would suggest is to apply thin acrylic medium layers that can readily penetrate into the plaster repair work. High Flow Medium would work well, or use a thinned medium like Fluid Matte Medium, GAC 100, etc. Once the dry surface begins to look sealed, then you may move onto paint mixtures, and then you can try to unify the sheen to your liking. IF the rest of the piece is able to be coated, you might want to give an all over varnish application (such as the Polymer Varnish Satin or the Archival Spray Varnish Satin) to further unifity and hide the repair work. Let me know if you have any other questions!
– Mike Townsend
Thanks for the article. What about using oil paint on top of plaster, does the plaster need to be sealed in any way, perhaps with a few layers of thinned GAC, or will the oil soak into it and form a solid substrate for further painting?
Hi Scott.
Thank you for your questions. I do not know if oil will harm plaster but being so highly absorbent it would be a good idea to seal the surface prior to using the oil paints. Seal with GAC 100 (diluted as necessary). After 2-3 coats of the GAC 100 you might want to use the Fluid Matte Medium as a transparent gesso layer before beginning applying the oil paints. You could also use acrylic gesso if you are not opposed to working with an opaque layer. Thin the products to retain the cast surface as best as possible.
– Mike
It seems as though I can touch up a plaster garden statue using a few layers of gesso, first, then paint with my acrylics. Yes? OR do I really need to spray on some varnish (before & after?) like I use on my hardboard signs?
Hello, Susan.
Thank you for your questions.
If you want to repaint exterior plaster statues, you’d be best to use exterior plaster or masonry primers instead of using artist gesso. There are stucco repair products such as Ready Patch and primers. Then, the acrylic paints may be used over them for the coloration, and a varnish such as the MSA Varnish can be applied at the end. Please contact us at [email protected] if you have any further questions!
Regards,
– Mike Townsend
hi! i have a question.
i am planning to paint on gypsona. the gympsum bandaids you get from a pharmacy for casts. i layer 2-3 strips together with water till it dries and becomes a solid surface. now i would like to paint on this textured surface with golden acrylic paints. should i layer it with acrylic medium gel? as a binder? please let me know how this surface can be made archival!
thank you so muc.
Hello Rabia,
Thank you for your questions.
I do not know enough about the Gypsona plaster materials to be able to discern if they are or can be made archival in regards to an artist application. However, they have been used by artists such as George Segal for use in lifecasting projects. I would assume that with proper sealing and protection via acrylic products and varnishes they should fare well in an interior setting. I recommend researching conservation efforts previously done on artworks where this product was the main material and see if the conservators mention the issues faced during restoration.
– Mike Townsend
Can I use white glue as a sealant on my plaster of Paris cast before painting
Hello Mary,
PVA (white glue) is water sensitive, so when you start painting with water-based acrylic paints over it, you may resolubilize the glue. Swelling glue could cause the paint layers to crack. Testing this application is highly recommended. Preferably the use of a thin or diluted acrylic medium would be a better choice as acrylics are not water sensitive once allowed to cure sufficiently.
– Mike Townsend
Excellent write up guys!
Is it possible to use POP to make pots/planters?
It’s a heavily moisture prone application, so will any type/amount of sealing will help me achieve this? I’m planning to use the methods suggested here to fill pores first with thin material and paint with acrylic paints and then seal with varnish. Any help is appreciated.
Thanks, Erik.
Plaster of Paris usually doesn’t fare well in exterior situations. Even high humidity can cause it to soften. Hydrostone and other plasters are probably better choices, or use resins from companies such as Smooth On.
Mike
Could you advise me please! I’m making plaster casts of flowers by making impressions of them in clay then casting with crystacal R. It dries really white and I want to maintain this finish, but I’m not sure what to use to seal it plaster. I want to keep a matt finish and not alter the colour.
Many thanks for any advice.
Hello Claire.
Thanks for contacting us with your questions.
If you are making pieces to be displayed inside, you can try the GOLDEN Archival Spray Varnish. Start with gloss varnish to seal the absorbency, allow the layers to dry and then switch to Matte. This may seem counterintuitive, but it reduces the chance of frosting that can occur when you directly apply a matte varnish onto a highly absorbent surface.
– Mike Townsend
I really never thought of working with plaster but article like yours are really motivating. There’s been a room in my house that needs it’s walls to get fixed I am definitely going to try out your methods. However, can you suggest me some way I can create different patterns on the walls?
Hello Gavin.
I’m glad I was able to inspire you. What are the kinds of patterns you would like to do on your walls? 3-D relief plaster work or more decorative with just thin paint layers?
– Mike Townsend
A very useful and practical issue.
Having embarked on some plaster of paris with acrylic inks etc I have lened some new ways of application and means of added strength
Thank you
You are very welcome Steve.
Thank you for your remarks.
– Mike Townsend
We are looking for the painting in the plasters of our building. It is really a useful technique for the painting plasters. Thanks for sharing this post.
Thank you for your comment!
– Mike Townsend
New to plaster. Using “Perfect Cast” to experiment with making some coasters. I plant to dot or mandala paint with acrylic. Do I need to bake them to set the paint and, what should I finish with to make them durable as coasters? Thank you so much for all of the information above. Really excited about this new project.
Hi Cheryl.
Thanks for your questions. No, you do not need to heat set the artist acrylic paints as they “coalesce” from evaporation of water and other additives. However, these are flexible, soft acrylic resins so they won’t crack and peel when flexed (such as on canvas paintings), therefore a clear topcoat should be applied to reduce the tackiness and make them easier to clean. A waterborne polyurethane, or acrylic/polyurethane blend (such as “MinWax PolyCrylic”) is always a good idea when using acrylics on functional objects. Waxes may also be used. We suggest the Renaissance Wax that is very easy to apply. – Mike
Michael,
I have a carved wood sculpture figure that the head and hair are made of plaster. I have painted the plaster with acrylic paint. This sculpture is to be mounted outside on a tree stump. How best do I waterproof the painted plaster and varnish the cherry wood figure. Thank you for your help.
Hello David.
Thanks for your comments and questions. If the plaster is already painted it will make it difficult to saturate the plaster with something to reduce water absorbency, which can really cause issues. Therefore, you need to seal the painted plaster with a very tight coating. A 2-part automotive urethane would be a good choice, but be sure to coat the entire piece well and not leave any areas uncoated, as that is where moisture will enter. If you do not want to have the gloss look, you can additionally apply the GOLDEN Archival Spray Varnish which is available in Gloss, Semi-Gloss, Satin and Matte. The cherry wood could be also coated with the urethane, but you could also coat with a Spar Marine Varnish if you don’t mind the color changes to the wood.
Hi. Great article. I’ve been using Crystacal R for approx 2 years making test casts from moulds. I’ve been trying out various methods prior to using crystacal for a project im due to start shortly where I plan to sell figurines etc. I’ve been using acrylic paint and never seen a reason as to using any primer to begin with. All you need to do is apply 2-3 layers of good acrylic paint then varnish. Why do you recommend primer when some of the best plaster is white anyway and the fact plaster is porous means it will absorb the paint far easier so isn’t going to crack if say compared to using something alternative like resin. Plaster will always be prone to scratching so if scratched this will remove the paint and plaster…not just paint so applying a decent varnish makes it a little less prone to surface scuffs/light sratches.
My question to yoy is you mention that plaster can take up to a month to cure. I am looking to make personalised sculptures for clients whereby I have approx 7-10 day turnaround. I’ve done various tests where I’ve made a cast from a mold same day and painted it that evening. Applied the varnish the following day and so far my tests have never deteriorated or had issues. I just wanted to know your thoughts as to how people are supposed to make casts and paint within a given time frame. Waiting a month is completely impractical but I completely understand that plaster has a drying out time. Would leaving a small area unvarnished in a certain place allow the air to get to the plaster so as to allow it to dry better let’s say if I was working on a 3 day turnaround? I want to start selling my sculptures soon but the only concern is the issue of when a sculpture is ready to send out. As previously said, all my tests have never had any issues so far when painting and vanishing shortly after casting but just want to know if there is anything I’ve missed before I commence selling to the public.
Thanks, Dave for your comments and questions. Plasters have a range of curing times, and the slowest drying ones may take up to a month to fully cure.
Crystacal R is a formulated hemihydrate plaster used in the manufacture of glass-reinforced gypsum structures, decorative plasterwork, giftware, and dental models. It is designed to set up quickly, so there would be no need for a month-long full-curing time before painting. It would still be wise to allow the cast to cure for a week, but this doesn’t mean you have to wait a week before painting with acrylics. If you are shipping in as little as three days, that’s certainly your prerogative but I would suggest careful packing as you would be shipping when the object is still a bit fragile. The curing isn’t dependant on oxygen as it’s a chemical reaction between the water and gypsum.
I agree with you that priming the plaster with gesso isn’t a necessity, but the first layers of mediums or paint need to be thin enough to readily penetrate into the plaster.
Many thanks for your detailed reply. I am still learning the ropes with using plaster and have tried a number of different plasters but feel Crystacal R is best suited for my requirements.
Is there any way to stop plaster scratching when painted? All the varnished I have tried using work fine as a sealer either gloss or Matt and give a nice finish but they don’t exactly stop light scratches. If you run a finger nail down the paint it removes and also takes a slight bit of the underplaster leaving a small white area. This isn’t great if I’m looking to sell to customers and sculptures take a few knocks and scratches.
Because I work from home and in a relatively small enclosed space I have been using water based polyurethane varnishes which are non toxic and fine to use indoors however there must be some kind of better sealer that leaves a harder finish so say for example a finger nail can’t leave the kind of indentation I’m currently getting.
If you could please advise.
You are most welcome Dave.
This is why tinting the plaster with an appropriate base colorant can help at least hide the scratches and minor chips. If the color isn’t deep enough, the next step is to do a dip stain with acrylic paints (for example High Flow Acrylics with a bit of water or Airbrush Medium). This is a quick process and you can put the pieces in a wire basket and dunk them into a bath of the color stain. You might also want to try tinting the polyurethane. Bear in mind that most of the commercial polys are actually a blend of acrylic and polyurethane, such as Minwax PolyAcrylic. Take a look at the products sold at Target Coatings and General Finishes, both companies make some great waterbased products.
– Mike Townsend
Many thanks for your detailed reply. I am still learning the ropes with using plaster and have tried a number of different plasters but feel Crystacal R is best suited for my requirements.
Is there any way to stop plaster scratching when painted? All the varnished I have tried using work fine as a sealer either gloss or Matt and give a nice finish but they don’t exactly stop light scratches. If you run a finger nail down the paint it removes and also takes a slight bit of the underplaster leaving a small white area. This isn’t great if I’m looking to sell to customers and sculptures take a few knocks and scratches.
Because I work from home and in a relatively small enclosed space I have been using water based polyurethane varnishes which are non toxic and fine to use indoors however there must be some kind of better sealer that leaves a harder finish so say for example a finger nail can’t leave the kind of indentation I’m currently getting.
If you could please advise.
Hello David,
Thanks for your comments and questions.
The type of plaster used has much to do with the resistance to scratching. Make sure the sealing coats saturate the plaster long enough to penetrate into the plaster to create a thicker “shell” to increase durability. Of course the pitfall of doing this is that some plasters are more water sensitive than others. Hydrostone is pricy, but by far it’s much stronger than plaster of paris.
Many thanks again.
One final question which if you could answer would definitely save me some money and time. Ive seen online that some people have recommended applying gesso or an acrylic modelling paste to plaster. Either would be applied onto the plaster then painted and this would leave a harder coating underneath.
I’ve never tried but could either be successful or something alternative whereby there was a harder coating between the plaster and paint then finished with a varnish sealer over the top so if scratched would not actually scratch the surface of plaster?
Hi David. My concern with applying thicker products like Gesso and Molding Paste is that it’s going to cover over the casting details, which seems to be counterintuitive to making casts out of plaster. Additionally, it would be another step that isn’t necessary as thin acrylic paint layers will absorb and adhere perfectly fine without the use of a primer. Thin, washy stains will penetrate into the plaster and tint it as well. However, this is why in the article I explain why adding color into the slurry mixture to tint it before casting helps hide chips later on.
– Mike Townsend
Nice Blog!! The content you have shared is very elaborative and informative. Thanks a lot for sharing such a great piece of knowledge with us.
An amazing article. It’s nice to read a quality blog painting plaster with acrylics post.I think you made some good points in this post.I have known very important things over here.Thank you so much for this post.
I have enjoyed reading this report about plastering services. Really it is more useful and also helpful. I am very glad to go through this kind of informative article. Thanks for sharing a nice blog.
Thanks for having this article, it helps a lot. It’s a well-written blog and it is very informative. Keep on blogging, looking forward to see more of your posts!
Thank you, Barry.
– Mike Townsend
I have a diy plaster stair molding hand holding craft kit. I was told special base coat is needed for plaster before apply folk art acrylic. So I made a trip to Craft store. They told me no base coat needed but to apply Folk art acrylic Then on top of it apply mod podge. I tested the folkArt acrylic by paint on the base on the hand. It was A bit difficult to paint on a plaster being that it’s a chalk like. I allowed it to dry. As soon as it dried I could even peeled off!? What went wrong? Thank you for your advices in advance!!!!
Hello Adriana.
Thank you for your questions. I cannot speak to other brands’ products, but the key to proper adhesion is that a thin acrylic medium or paint can penetrate into the plaster, as outlined in the article. Diluted Modge Podge (there are several products offered) that are acrylic based mediums, can be thinned with water and glazed onto the cured plaster, then paint layers can adhere better to it.
– Mike Townsend
Hi Mike thank you so much for the article as it’s very informative. I’m new at working with plaster so please bear with me. I used folk art acrylic directly. Allowed it to dry. It actually peeled off after couple hours. Tips? Very much appreciated. For some reasons it seems like my messages won’t go through. I see last person comment was in 2019:/
Hi again Adriana.
Please review the comment of yours that I responded to. Sorry for the delay!
– Mike Townsend
Hi, Mike. I created a life cast with hands. I want to seal it and make it waterproof, because I need to make a duplicate of it by recasting it in the silicone mold. What can I use to make it waterproof? It’s my only copy, and I’m trying to make a duplicate to then send off in the mail and have bronzed. (like they used to do baby shoes). Thank you so much!!
Hello Elise.
I would suggest using a spray polyurethane https://www.rustoleum.com/product-catalog/consumer-brands/specialty/polyurethane-spray/ or an acrylic enamel (such as https://www.duplicolor.com/product/acrylic-enamel/). Polys tend to be very tight coatings, and spraying several light coats should help seal the surface without creating brush strokes or hopefully the loss of detail. I would highly suggest testing and practicing on similar casts to assure you are pleased with the results, as you’ll only get once chance on a one of a kind cast.
Let us know if you have any other questions!
Regards,
– Mike Townsend
Hi, I’m creating plaster cast plaques, and I want to apply an acrylic wash to them for a soft, colored effect. Does the plaster need to be sealed first? Thanks for your help.
Hello, Nancy.
Thanks for your question.
No, you do not need to seal the surface first. In fact, the unsealed surface will stain really nicely as the color wash absorbs in readily. If you do a lot of these, you might want to make a “dip-tank” to dunk the object in and then remove and let drip dry. The longer you leave the object in the tank, the more intense the color saturation would be. The wash works well if you also add some additional acrylic medium, as this helps to seal the surface at the same time you colorize the piece. contact us at [email protected] if you want to get into any further detail.
– Mike Townsend
Thank you very much!
Hi Michael,
You have some very informative replies over a year ago. I have been following advice with regards to adding a couple of drips of acrylic paint into the plaster and water mix so as to tint the plaster. I’ve been trying to get a concrete effect and by adding a few black drops it’s worked great, however what I’m finding is that the plaster feels quite chalky even when dried over many days. If you scratch the plaster its so noticeable and the scratches far more easily than unpainted plaster. Ii use crytacal r so it’s a very strong plaster in its natural unpainted form.
I’ve tried different brands of black paint and all leave the plaster chalky once dried. Is there a way to protect this plaster or avoid this issue.?
Secondly, and slightly off topic as it isn’t to do with painting plaster but when I remove some plaster shapes that have straight edges such as a rectangle, I’m finding that there is a slight bend or warp to a side. The actual mold doesn’t have this bend and it seems to happen when the plaster is drying. Do you know what could cause bends or slight warps as a few of my bases don’t sit properly now due to being uneven when they weren’t originally when pulled from mold. I’ve tried to sand them but this hasn’t completely levelled the base so as as the sculpture sits flat and I’m wasting alot of time and plaster.
If you could kindly advise it would be greatly appreciated.
Thank you for your comments David.
I don’t know that the black acrylic paint would cause the chalky surface unless the binder or matting solids are being pushed out of the mixture as it cures. I have never seen or heard of that occurring but that doesn’t mean that it could not happen. It may also be the pigment type. For example, Mars Black is an Iron Oxide black that can react with raw aluminium and cause a chalky residue to develop, especially in a moist, salty climate. What black pigments have you tried, and also, have you tried a black universal tint/colorant/dispersion? These would eliminate or verify that the acrylic binder is pert of the issue.
As to plaster warping as it dries. I’m not a plaster expert by any means, but extra water could cause more shrinking during curing, so watch the amount of water being added. Otherwise, it may be the scope of the project and you may need to use a 2 part expoxy system or something like that.
https://www.smooth-on.com/ https://www.polytek.com/application/crafts-hobby would be the brands I would contact to see what they know about both of these issues. – Mike Townsend
that’s actually a good idea. Good thing you included it here
Hi Michael,
I am using Hydrostone and would like to “paint” a pure white layer over it to cover up any blotching. Can you suggest what to use that would not leave brushstrokes…either the product or the brush? I feel like I’ve tried so many things, including an airbrush, but that takes soooo long to cover well.
Thanks,
Bonnie
Hello Bonnie.
What are you trying to coat? Shape, size, etc…
You might be able to pour the white paint over the piece and allow the excess to drip off. High Flow Titanium White might work for this, but please provide some additional details!
– Mike Townsend
Hi Michael – Great blog, very informative! I have a newly reproduced plaster base that was made to support a small, old artificial Christmas tree from the 1930s. The original base was lost.
Once I allow the plaster to fully dry, I want to paint it an antique white with a satin finish. What paint do you recommend, and should I seal it after with a varnish?
I use Golden paints and love them.
Thanks, Craig
Hello Craig.
Thank you for contacting us with your questions.
The white paint layers can be done with thin washy layers of the paints. If you can add some High Flow Medium, or GAC 200 into the paint mixtures that help to improve hardness.
For interior decorative work, a water-based polyurethane/acrylic blend varnish should be fine. MinWax PolyAcrylic is an easy one to obtain and may be used over our paints without concern of adhesion or ambering as it ages. Otherwise, you might find a lacquer sealer such as Duplicolor clear sealer. These products are often available in Gloss, Semigloss and Satin sheen.
Please let us know if you have any other questions.
– Mike Townsend
It is a nice article about three reasons about painting plaster with acrylics-2. I agree with all your points that you have stated here, love this blog. Thanks for this wonderful content for all of us.
Hi Michael. I left a comment yesterday which seems to have disappeared so writing it again. This has happened before when writing s comment. It shows up on here then the next day I can’t find it. Hopefully this comment stay up.
I’m looking for a powder to mix with crystacal r plaster to create a concrete colour effect. I’ve been using black acrylic paint in the plaster mix. The mixing of black acrylic creates a nice grey concrete colour but the plaster dried very chalky and scratches really easily even after a prolonged period of drying so it’s really not suitable doing this if I’m looking to sell my plaster items.
I think I recall you mention using mica powder mixed with plaster so as to colour the plaster. ..is this correct and would it not just give similar results to the issues I’ve already experienced when mixing acrylic paint? Can you recommend the most suitable powder colour for mid to dark concrete and also what brand or type of powder should be used.
Hello Dave.
Comments are reviewed before they are approved and responded to, which is why there was a delay.
I do not know why adding black acrylic paint would cause the plaster to become chalky, as it would be adding acrylic binder into the mixture as well as a black pigment. The darker grey color might be highlighting the inherent chalkiness of the plaster being used. You might want to try to paint the plaster with washy layers of black paint to create a deeper appearance, or mix the grey color you desire and apply that as washes onto the surface of the dry plaster. If you try dry black pigment, I would suggest a Mars (Iron Oxide) Black, as it is not as fluffy as carbon black, so a bit safer to handle.
Adding Mica may also work for you, as a powder form as opposed to acrylic paint containing mica. Here’s a nice black mica that is sold through Kremer Pigments: https://shop.kremerpigments.com/us/shop/pigments/50090-iriodin-600-black-mica.html
You can get small quantities to test, and then larger ones that work for you.
– Mike Townsend
Hi Michael
I made a plaster of paris hand cast and wanted to add texture to the back of the hand. I first added a coat of thin white acrylic paint, then I went in and added thick layers of acrylic paint. However, I then started to notice that the paint has shrunk, showed cracks and lifted up away from the plaster.
I wanted to know if there is a way to be able to still apply thick layers of paint, should I do one layer at a time to allow it to dry. Would it also work if I tried to mix glue with the acrylics as a way of getting it to stick to the plaster.
Thanks Tasmin
Hello Tasmin.
Thank you for contacting us with your questions. Yes, you can do this, but seal the surface with thinner layers of medium or paint with medium such as Fluid Acrylics and the High Flow Medium. This will serve as a primer sealer, and apply two thin coats allowing them to completely dry between coats and before you apply the thicker paint layer. – Mike Townsend
Hello Michael,
Just wanting to know If I could also use homemade gesso at a seal for a cast.
The gesso I made consists of; water, powdered chalk, white acrylic and PVA glue. However, when I applied this to my plaster of paris hand cast it got more textured and clumpy.
Also will this type of gesso help the paint to stick to the plaster of paris.
Thanks
Tasmin
Hello, Tasmin.
Plaster of Paris isn’t waterproof, it’s not even water-resistant. The surface should be sealed carefully with a layer of acrylic medium or paint to reduce this sensitivity and also to reduce water absorbency. Also, be sure to mix your gesso and plaster mixtures really well, until it’s smooth. Start with the water, then add the PVA, and then the acrylic paint. But stir each mixture really well before moving onto the next ingredient.
– Mike
Best of information regarding the painting plaster with acrylics 2. In order to get better information and guidance can be taken from this blog specifically. It plays a vital role in taking us through. It can be really great for people like me who are looking for grabbing more knowledge about.
Hello, Mike.
I inherited a 9″ plaster cat. It’s been broken and mended, with about a 1″ square area of small chips on the back that have left a 1/8″ gap in the mend, like a small divot. It’s painted, but the original finish is kind of a scuffed and dirty looking cream color, shiny on the head and matte everywhere else.
I’d like to repair the “divot” in the mend and repaint it. It sounds like if I mix up a bit of plaster, I can fill in the divot and then sand everything, but I’m not sure if there’s anything I need to do before I repaint, beside dust it off.
Appreciate your advice,
Chris
Hello Chris,
We have not done repairs on plaster, and so cannot really advise on the best approach. We also are not sure what type of paint might have been used, and whether acrylic would adhere well to the surface. An art object conservator would be better able to address repairing the statue. The American Institute for Conservation (AIC) has a “Find a Conservator” webpage which might be helpful. MITRA, an art conservation forum at the University of Delaware, allows people to ask questions which they then answer. This also might be a source for information on how best to patch the plaster sculpture. We hope one of these will be helpful!
Nice blog. Happy to see your idea of writing blogs. It seems easy but it is not as the painting have to match the color as the house owner wants and the color preference is different of all home owner. Around a year ago I hire a painter on the recommendation of my relatives but not got the desired results as I was expecting. But now I understand that no one can full fill your all expectation in any field.
Very nice blog. I am glad to hear that you are interested in writing blogs. Although it seems simple, it can be difficult as the paint must match the home’s color preferences. A year ago, I hired a painter based on recommendations from my family. However, I didn’t get the results I expected. Now I know that no one can fulfill all your expectations in any field.
This is a great article! These services are definitely worth considering. Before hiring a painter, I will make sure to follow your advice and ask my family and friends. Thank you for sharing.
“You are an inspiration to my children and me. I have always enjoyed reading your books to them at night.
This topic is very interesting, I was able to learn a lot from this content. And I was able to learn that shellac is used as a plaster sealer. Are you also a painter too?
I wish I could write anything close to that. That’s too good!”
Hello, Dana.
Yes, I am also a painter. Writing well is a similar process to painting; the first 3 drafts are nowhere near as eloquent as the completed work.
– Mike
Hi Michael,
I would like to tinty plaster with a skin tone. I’ve tried painting but finding it takes 2-3 coats + am initial coat og gesso. It’s not. Practical when I’m selling these items for very low prices. In the past I’ve tinted with black to create a concrete effect which comes out great but I’ve used powder paints and just add the powder by eye sight until the colour looks the desired effect. Unfortunately for the skin tones I require these are not available in powder format, only liquid poster paint. I can’t figure out the correct mix to get a good strong colouring that would look like it’s been painted.
If my plaster to water ratio is 100:35 and the overall weight of plaster used is say 150grams, then I would normally add say approx 52g of water. If I added say 3-10 grams of poster paint do I have to increase the amount of water aswell to compensate?
Hello, David.
Thank you for your questions.
Usually you do not modify the amount of water to plaster when adding paints into plaster. Measure out the amount of water, then add the paint into it and mix until homogenous. Then combine the paint water mixture with the plaster.
– Mike Townsend
This article brilliantly illustrates how acrylics can transform plaster surfaces into stunning artworks. The detailed steps provide a clear guide for both beginners and seasoned artists to experiment with texture and color. It’s inspiring to see how versatile acrylics are in elevating ordinary surfaces into captivating pieces of art. Great job!
I found your article on painting plaster with acrylics incredibly informative! Your detailed explanations about the preparation process, especially regarding the need for proper priming and surface treatment, are vital for achieving a smooth finish. As someone interested in stucco, I’m curious about the differences in applying acrylic paint on stucco surfaces compared to traditional plaster. Do you have any tips or specific techniques for ensuring the longevity of the paint on stucco? Thank you for sharing such valuable insights!
Thank you for your comments and questions.
Stucco and other absorbent products like dry wall mud need to be sealed or they can continue to absorb moisture and embed dirt and grime. Sealing the surface with an exterior grade commercial sealer before priming and painting is a good idea, but even if you wish to retain the original look of the stucco layer, use a clear masonry sealer, which are often made with 100% acrylic binders, such as Ben Moore’s Ultra Spec 100% Acrylic Clear Masonry Sealer
– Michael Townsend
This article offers a fantastic, comprehensive guide to painting plaster with acrylics. The historical context, technical insights on sealing, priming, and layering techniques, as well as product recommendations, make it a valuable resource for artists working with plaster. The emphasis on drying time, absorption levels, and using specific acrylic products like GOLDEN Airbrush Transparent Extender to improve durability is particularly helpful. The step-by-step explanations ensure even complex processes are approachable, and the guidance on strengthening plaster with an acrylic modifier is an insightful addition. Great work providing such in-depth, practical advice!