Cures for Calcimine Ceilings

If patches of peeling paint on a ceiling or flakes of paint chips littering the room is a familiar site in your old house, your ceiling likely has a past that includes calcimine paint. Used throughout the 19th and into the early third of the 20th century, calcimine paint was a very popular and economical solution to give interior surfaces a fresh coating. Also referred to as kalsomine or distemper paint, it was a dried calcium carbonate product that, mixed with water and sometimes pigments and glue, formed an opaque, easy to use and fast-drying coating for walls and ceilings. These were the days of heating with coal and wood stoves, so walls and ceilings stained with soot quickly and calcimine was a quick and inexpensive cover-up during spring cleaning. Another aspect of its appeal is that it could be used immediately over new plaster as a coating. The plasters used during these times took anywhere from 30-60 days to fully "season" to the point that the PH-levels in the plaster compound would accept oil-based paint. Otherwise, the paint would become blotchy, blister and peel off as the curing plaster reacted with the oils in the paint. So calcimine provided a soft look to the stark plaster surface, and allowed builders and homeowners to "finish" their project immediately.

Being essentially chalk, the water-based mixture of calcimine paint contained minimal binders and glues for adhesion. Herein lies the problem for those of us dealing with peeling paint now, because this lack of active binder chemicals discourages modern paints from adhering. Over time, any paint coatings over a calcimine base will fail, chipping and peeling away modern paint coverings have nothing to "stick" to. Also, it is a very soft coating and all of today's paint products are harder by comparison. A harder and stronger product cannot be layered successfully over a softer and lighter product because its surface tension will cause it to pull away. Environmental and climate changes (temperature shifts, unheated rooms during winter, moisture and humidity) also accelerate the delamination process significantly. The consequences of each of these scenarios are lots of peeling and large flakes of paint simply falling away from the wall or ceiling surface.

There are no easy or quick fix solutions to removing calcimine coatings. To achieve a smooth and long-lasting painted surface, as much of the calcimine as possible must be removed for any paint to adhere. This is a messy and time-consuming project, but well worth the effort. Another approach involves "locking" the calcimine onto the surface by sealing it with calcimine-coater or an oil-based primer. Both these approaches have advantages depending on your particular situation and energy level for the project. It really depends on if you are trying to cover over a problem or get rid of the problem, and how smooth you desire your finished ceiling to be. Simply repainting the surface will not, unfortunately, make your problems go away. You also do not want to begin to sandwich oil-latex-oil paints because they 'move' and react to environmental changes differently so this will only worsen your peeling problem. We will describe the two approaches we prefer when dealing with that determined-to-peel calcimine.

The first step is to determine for sure that you are dealing with a calcimine problem, and what has been coated over it. Because it is essentially chalk, calcimine can easily be detected by rubbing a damp finger (sure, spit works) or a sponge on the surface and looking for a chalky residue. Just like if you wet your finger and rubbed a dirty chalkboard, imagine the way the chalk would look and feel on your finger. To determine the paint products used since, we use rubbing alcohol and/or a chip-test. You want to use a cloth or rag that is distinctly different in color from your surface so you can plainly see the results of your testing. This cloth can first be dampened in a small area and rubbed in a peeling spot to determine the existence of calcimine, then using rubbing alcohol, rub to analyze the paints used. Oil paint will not be affected by the alcohol, whereas water-based latex paints will dissolve to some degree. The alcohol will cause latex paint to get sticky and rubbery (like an eraser), and you will begin to see the paint move and become pliable as it softens.

In the early part of the 20th century, oil paints became popular. The first few coats of oil paint would penetrate through the calcimine and hang on for several years, and the strong binders in oil paint also assisted in temporarily binding the calcimine to the surface. However, eventually oil will oxidize as the oils break down and dry out, and will begin to peel away. Oil paint dries to a firm, stiff finish, and will likely chip and flake away in small pieces. The chips will feel very brittle - crunching between your fingers.

Your Calcimine Weapons! (L-R):

  • 6" Taping/Joint Knife
  • 1" Putty Knife
  • 2" Carbide Scraper
  • 3M Doodle Bug Pad and Pole
  • Large Block Sponge

Modern, water-based latex paints have the least chance of maintaining a surface over calcimine. They cannot penetrate through the chalk of the calcimine, and the water content in these paints also assists the calcimine in letting go. Latex paint can begin to bubble and peel away almost immediately over calcimine, and after a seasonal temperature change, watch out! We often hear clients lament, "but I just painted it last year!" Latex paint dries to a flexible, elastic finish, and creates a stretchy surface tension that causes it to peel away much faster and in larger pieces. Latex chips will feel slightly elastic and pliable.

Sometimes, of course, there will be coats of oil paint followed by coats of latex over the last decade or two. With this scenario you will see a chip with a crackled base (the dry oil paint), and a stretchy, more intact top layer of paint. The rubbing alcohol experiment will result in some paint removal of the top layer(s) of latex paint, then it will stop removing any paint when it reaches the oil layer.

Complete Removal Method
If you really want to get rid of the calcimine problem, then you will need to scrape off all the paint and calcimine, and use water to release the calcimine during a series of scrubbing efforts to remove it. This will get you back to the original plaster surface to work with for a fresh starting-point. This method requires a significant amount of elbow grease, lots of water and detergent, and patience with a time-consuming process. It is a very messy and wet process so be sure to adequately protect floors, woodwork, furniture and fixtures in the removal area.

You might want to begin by going through this process in a "Test Area" of your room, perhaps a corner or less visible area during your learning curve. This will help you develop a scraping technique that does minimal damage to the plaster, give you a sense of how much scraping to do before you reach plaster, and get a feel for the difference between paint, calcimine and plaster. You will become very motivated to know when you have done enough scraping and when you can stop!

Using a 6" taping knife, scrape all the loose areas.

(Step 1) Begin by scraping all visibly loose paint using a sharp putty knife or razor knife. If it is really peeling readily, start with a 6" joint compound knife.

Carbide scrapers work best for scraping off stubborn paint layers and getting at the Calcimine layers.

Once you get down to more stubborn paint and the calcimine, go to a smaller 2" knife. We prefer a carbide scraper (Sandvik brand) for this; maintain a careful hand not to damage the plaster unnecessarily. Some damage to plaster is inevitable, and these blemishes can be repaired once the calcimine removal process is complete. Continue to scrape through the layers of paint, and as you reach the calcimine level you will notice more dust being generated - that is the chalk coming off. You will begin to see the plaster beneath, and the scraper will stop generating the chalky dust. The surface will begin to feel differently, and you can see the white lime coat or a sandy look.

Designed for Marine purposes, the 3M Doodle Bug abrasive scrugging pads on a pole work great for the scrubbing and sudsing steps.

(Step 2) Once you feel you have scraped as much as you can get off, you will begin the scrubbing and washing part of the process. The water will activate the calcimine and encourage it to continue to come off the surface. Wash all surfaces with a detergent soap (Spic and Span, dishwashing liquid, TSP) using a scrubbing pad. We use a 3M brand scrubber called a "Doodle Bug" which is actually designed for the marine industry. Really scrub at the surfaces, and use a detergent that will generate as much as sudsing action as possible. You want to generate a foamy-froth with your scrubbing. This sudsing action keeps the surface wet longer, and will help the calcimine let go.

Using a large sponge, squeegee off the foamy suds to release and remove the calcimine.

(Step 3) While the surface is still foamy, use a squeegee tool or large sponge to remove the foam and water. The Calcimine has been suspended during the sudsing. It is important to remove these Calcimine particles before the plaster pulls it back into the surface. Repeat the scrubbing, sudsing, squeegee process several times, using clean water and fresh detergent each time. Usually 2 - 4 wash/scrub processes are necessary.

(Step 4) Once you feel you have everything removed, do a clean water rinse of all surfaces using a very clean sponge. Note the amount of murkiness in your rinse water - murkiness indicates you have more scrubbing to do! Complete with one final clean-water rinse.

At this point, let the surface dry completely for a few days. If you worked through the removal steps diligently, there should be no additional peeling. Test your calcimine removal success by firmly rubbing a dark cloth or your finger across the surface in a few different places and look for a chalky residue to appear. If chalk appears, you still have more scrubbing to do! It is next to impossible to get all of the calcimine off, even after you have scraped and scraped, and washed and washed. Eventually you will give into "that's good enough!" Our goal is to remove all of the old paint and calcimine, and realistically end up somewhere in the 80% area. Then we relying on oil-based calcimine coating paint or oil primer to make up the difference.

At this point, you can complete any plaster repairs that may be necessary. Take care of gouges and blemishes caused by the scraping by using a sandable Durabond. We prefer Durabond for this because it has its own bonding agent, sets up quickly, and requires less sanding. Cracks can be dug out and repaired at this time as well.

When you are ready to repaint your removal areas, use a calcimine-coater paint if available. They can be tricky to locate, but it will be worth it. They are developed to penetrate through any remaining calcimine and seal it in, and also do not require further paint so with one coat you can be done. They have a soft look and yellow slightly so they offer an historic look to an older home. Some of them are made to go over with a top-coat paint and some are not so read the labels carefully. Look for California's Oxiflow or Muralo's Calci-Coater paints. Larger home and hardware chain stores (Home Depot) carry a calcimine coater in their Sterling (SCL), Old Yankee paint line. Check with your paint dealer for availability of these products, and go with the best brand from a specialty paint store if possible. If these products are not available, then prime all removal surfaces with an oil-based primer that can penetrate and seal the calcimine also. If staining is an issue, be sure to use an oil-based stain blocking primer (we use Bruning's Synthetic Resin Stain Blocker). Oil-based primer can then be followed by a latex or oil paint topcoat of your choice.

Cover Up Method
If you are trying to cover up the problem, then you can go with a less time- and energy-consuming approach of just scraping what is loose, washing the calcimine from the scraped areas using minimal water, and then sealing it with a calcimine coater or oil-based primer paint. This may work nicely for many years (we used this method on a ceiling that is ten years and holding), or it may not be successful - particularly if there are drastic climate changes or moisture present. If you have a very small area that is peeling you might want to start with this approach.

Once you have scraped off everything that is loose, you can either scrape off the calcimine (see Step 1, above) or gently wash just those areas where you scraped paint away with a damp sponge and some detergent to remove the calcimine chalk. If you scrape the calcimine away, lightly damp sponge off any sanding dust. Wait a day for everything to dry completely to check for additional peeling. The more washing you do, the more calcimine will lift off and your peeling areas will grow. If you are sure you have gotten off everything that is loose (rub around the chip area with lightly with your finger tips; it will sound like rubbing a piece of paper if the paint is still loose), and scraped or carefully washed off the calcimine from these areas, go over with a calcimine coater paint (or oil-based primer if you can't find a coater), and let it dry completely. Now you have sealed the calcimine in. You will have blemishes and shallow craters on the surface where the paint chips were. If these are aesthetically unpleasing to you, you can fill them in for a smoother surface. We recommend a vinyl-based paste or spackle compound instead of a water-based joint compound, because any additional water applied to the surface can activate the calcimine. Fill in the desired areas, let dry completely and lightly sand with a 120-grit sanding block. Then gently damp-sponge these areas to remove sanding dust, followed with another coat of calcimine coating paint (or oil-based primer) for the final sealing. If you are using an oil-based primer, you need only re-seal the areas where you in-filled the craters. At this point you can go over it with a flat, latex ceiling paint if you choose.

This article is also available in print in the April 2001 issue of Old House Journal.

©Copyright 2002 Peter Lord Plaster & Paint, Inc. • 24 Moody Road, Limington, Maine 04049 • (207) 793-2957