Q: I have painted drywall in my home and would like a lime plaster finish. How can I achieve this?
A: There are many ways to achieve a lime plaster finish over painted drywall. The first issue to address is who is going to do the work? If you hire a good plasterer then they should know how to approach this issue. Even still, you could enlighten them with new products that they may not know about, that you have discovered in your research. If you are a more do it yourself kind of person with some trowel experience than you might be surprised what kinds of finishes you can achieve with a little bit of practice on some 12” x 12” sample boards.
How you ultimately approach, this task is dependent on three major factors… budget, authenticity and texture. Depending on the budget allocated toward a lime plaster finish, a person can achieve a wide range of finishes. The polished mirror finishes often-associated Venetian plaster can but not always be associated with higher costs. This is due typically to higher materials cost and higher wage costs because of the skills required to achieve that level of finish. Speaking of wage costs it should be noted that ceiling applications are much more labor intensive, rightfully so and should probably left to a professional plasterer. A rougher coarser finish can hide slight imperfections in artisanship, thus it typically costs less than other finishes. Since we have now linked the relationship between budget and texture to how you can achieve a lime plaster finish over drywall, it is time to move on to authenticity.
Authenticity refers to the quality of the product. Is it lime, acrylic, or a blend? Sometimes authenticity does not matter however; with the ever-increasing customer demand for low or no VOC products, it may play a role in your decision-making. There are flexible “lime” plasters that have chemical additions as well as many acrylic based bonding agents available on the market. If you want a more real lime plaster system on your painted drywall, than LimeWorks.us has a solution for you.
You should begin with a clean sound surface, free of any soaps or detergents and of course with no pealing or flaking paint. A quality finish is only as good as the quality of what is beneath it. Then simply trowel apply TakcoatTM evenly over the entire wall 1/16th to 1/8th inch thick. This will act as a transition coat from paint to plaster. TakcoatTM uses hydraulic lime and natural additives to achieve a bond that can stick to glass, ensuring a good bond to the painted wall. Once the transition coat of TakcoatTM has cured for a about 3 days, a second coat of lime can be applied to achieve the finish. Depending on the what the kind of finish is desired another coat of lime can be applied, or even three, four or five. It all depends on what you or the client wants.
If a rough finish or soft-sanded finish is desired than Ecologic® Mortar in either coarse or fine sand can be applied. If a fine polished, finish is desired than NHL 2 can be applied paper-thin in multiple coats to create depth to the finish, which is polished with black soap diluted with water. all of the products mentioned can be blended together to make the right finish for you or the client. Custom colors can be matched for you, or you can add your own iron oxide or natural lime proof pigments.
Because of all the case specific challenges, answers to this FAQ are just a basic overview. If you plan to tackle this issue head on, give a call or shoot an email to randy@LimeWorks.us. We can help you with choosing the proper products and application techniques.