What’s the most efficient way to remove old paint, stain and varnish? Which stripper works best? Should I try a heat gun or how about sanding? I have the answers because I’ve tried them all . . .
So it’s time to refinish grandma’s dresser. In my case it’s a hope chest given by my father to my mother as an engagement gift in 1935. In this article I am going to cover the first step in the furniture refinishing process – stripping old paint or varnish. Most consider the stripping old paint and varnish the most tedious and messy step in the furniture refinishing process but it doesn’t have to be.
You’ll find this, as all my articles and videos a detailed step by step guide to removing top coats, both paint and varnishes. As an option you can watch my YouTube video “Chemical Strippers vs Heat Gun – Furniture Refinishing” where I visually demonstrate the correct steps in assuring a quality finishes.
There are two basic ways to remove an old finish:
SAND IT OFF
Sanding takes a ton of time and effort so unless you are doing a small project with not a lot of top coat left this would be my last choice.
MELT IT OFF
That’s right I said melt it off. Melting the old surface can be accomplished in one of two ways, by very high heat using a heat gun or chemically using chemical strippers. This is the most sensible way of furniture refinishing.
First let’s look at the materials you’ll need:
Chemical stripper or a Heat Gun
Glass or metal bowl (not aluminum)
Cheapo Applicator Brush
Scrub Brush with stiff bristles
Stiff Tooth Brush
Catch surface with a flat edge (not aluminum)
Synthetic scrubbie pad
Lacquer Thinner or Mineral Spirits (Lacquer Thinner works 10 times better)
Tarp, plastic sheet or cardboard as a surface protector
Respirator (not a dust mask) or an electric fan with fresh air source
Garbage Can with a disposal plastic garbage pail bag
WARNING: Please be sure to read the precautions below as any chemical or heat source strong enough to remove paint has the potential to burn your skin, damage your eyesight and can create vapors which can be inhaled causing a myriad of respiratory and circulatory ailments. That said both heat and chemicals have been used for years in furniture refinishing and with precautions will cause no physical harm or ill effects.
Furniture Refinishing with Chemical Strippers
First a quick review of the types of chemical strippers available. Chemical strippers fall into three basic categories: Caustic strippers, Solvent strippers and Biochemical (Eco-Friendly) Strippers. Each has their pluses and minuses. For an in-depth description refer to Paint Pros Journal article Paint Strippers, Types of Strippers.
Caustic paint strippers
Caustic strippers use lye as their chemical base to remove old paint or varnish. Lye in its mildest form is used in soaps and in its strongest forms are used to open clogged drains and digest dead animal carcasses. The active ingredient is either potassium hydroxide (known as caustic potash) or sodium hydroxide (caustic soda). Caustic strippers soften the oily part of paint turning it into a soft soap-like material that can be easily removed.
Because they are soap based they must be thoroughly removed and neutralized or the next coating won’t adhere properly plus when using lye to strip furniture it tends to darken wood which may then require an additional process of bleaching the wood to restore its natural color. Thus for stripping furniture this would not be my choice.
Solvent paint strippers
Solvent strippers are my choice when using a chemical stripper. When shopping for solvent strippers check the label, the active ingredient in solvent based strippers is methylene chloride (dichloromethane). Solvent strippers use a variety of chemicals that act to break the bond between the paint or varnish and the surface of your project. The end result is it softens and causes the film to “bubble up” making it easy to remove.
Eco Friendly Strippers (Biochemical)
This class of stripper uses various plant based chemicals to soften the paint or varnish. The solvents in them are derived from plants. Biochemical-based strippers may include terpenes, from pine or citrus; lactic acids, from corn sugars; dimethylsulfoxide (DMSO), from wood pulp and paper by-products; citric acid; and soy oil. In addition these strippers typically contain non-natural chemicals to enhance reaction.
I don’t use biochemical furniture strippers as they are slow to work and extremely messy. All chemical strippers work when wet and fail when they dry out. Because the chemicals in eco strippers are not as harsh they require additional time to dissolve the old surface coating. Hence, there is an extra step of wrapping your project in cellophane or wax paper and leaving it on for an extended period to penetrate, usually overnight. Once the cellophane is removed there is a need to act quickly to remove the paint or varnish before the stripper dries and is no longer effective. This is my last choice in furniture refinishing.
Heat-Based Furniture Strippers
Heat works by softening or melting the top coat. The choices here are two. An open flame source like an old fashioned blow torch or a more modern electrical heat source like a heat gun. Both soften the top coat for easier removal and disposal. Because there are no chemicals this method tends to be a little more eco-friendly, although the vapors emitted may well have atmospheric effects. Heat guns are slow and tend to work better on perfectly flat surfaces. Again, not my choice in removing paint or varnish.
FURNITURE REFINISHING PRECAUTIONS
Okay, I know nobody reads warning labels but in this case you should.
Chemical Stripper Precautions
Furniture strippers by nature have to be strong chemicals and all strippers pose a health risk when inhaled or splashed on your skin or eyes. It is important when using any method of removing old paint and varnish when refinishing furniture to do it in a well ventilated area, preferably outside, and to wear protective clothing and safety glasses. If at any time chemical stripper comes in contact with any body surface immediately rinse thoroughly in water.
As I mentioned, it is best to use chemical strippers outside. If you do have to perform the operation inside it is recommended that the air in the room be well ventilated and the air in the room be changed 7-10 times per hour. I like to use a fan at my back pushing the vapors away from me and out a window if possible. The last precaution is flammability read the manufacturers label carefully as you may need to stay away from pilot lights on furnaces, stoves and water heaters.
Heat Gun Precautions
The same ventilation precautions apply to heat guns. Heat guns operate between 400-1200 degrees Fahrenheit. Besides the capability of causing severe burns applying this much heat to paint or varnish can create toxic fumes so using a suitable respirator and operating with the same ventilation requirements as mentioned above are essential. The other potential risk is that of starting a fire. Remember too, older paints contain lead and inhaling its vapors poses yet another level of risk.
REMOVING OLD PAINT AND VARNISH WHEN REFINISHING FURNITURE
Heat guns work best on flat surfaces as the heat breaks the bond between the paint and the surface below. Hold the heat gun a few inches from the work surface and watch for bubbling. Once noticed test with a paint scrapper removing the paint from the work surface. The old top coat should peel away with minimal effort. Working in small sections is the only option as it takes a while to actually melt the top coat. Avoid overheating and potentially burning the surface below. Worse yet is the risk of starting a fire. Again the object is to free the paint from its surface and not completely melt it. If there is a lot of detail (carvings, bevels, rounded surfaces) in your project you may need to finish with a chemical stripper. Heat guns have certain advantages but they are slow when used in furniture refinishing, so not at the top of my list.
Follow the manufactures recommendations closely for application and timing. Eco-friendly strippers are considerably slower to react so they require an extra step. Because eco-friendly strippers are slow so there is the probability of evaporation. Eco-friendly strippers have to be covered with wax paper or cellophane wrap allowing them the necessary time to work properly.
My personal preference for refinishing furniture is solvent strippers containing methyl chloride. They require extra precautions but are the fastest and most effective.
All strippers work by forming an airtight layer between the suspended chemicals in the stripper and the paint or varnish. There are two types of solvent strippers liquid and semi-paste. I prefer the semi-paste as wax is added to chemical strippers to provide density necessary for vertical surface application and to delay evaporation giving the stripper time to melt the paint or varnish below.
Make sure your work area is well ventilated and all surrounding surfaces are covered with an appropriate tarp, cardboard or plastic sheeting. Have a proper waste collector ready for collection and disposal.
Use an inexpensive disposable paint brush and apply a thick coat. Apply as if you were layering icing on a cake. Apply in one direction only “laying it on” rather than back and forth strokes as you would if painting. Chemical furniture strippers work best if not disturbed or overworked. Once applied leave it alone. Most chemicals used in furniture refinishing require 15-20 minutes to work and work better at higher ambient temperatures. Check manufacturer’s recommendations for both. Once applied its best to leave the area to avoid inhaling fumes.
After about twenty minutes you should be noticing the old film bubbling up and separating from the surface below. It’s now time to gently place your paint scrapper blade at one end and very gently push the old film to the opposite end and into your disposal container. Continue removing until all the stripper and old film has been removed. Follow the manufacturers timing recommendations for removal but be sure to test a small area to see if paint or varnish lifts effortlessly.
Often a second and third coat may be required to remove all residue. Often when stripping old painted furniture the paint has been applied over a varnish or other clear top coat. Make sure you have removed both and are down to raw wood when done.
When refinishing furniture with rounded, curved, carved, etched or highly detailed you may have to use a scrubby pad, scrub brush, scouring pad, medium to fine steel wool or a tooth brush. When using be careful not to splash on exposed skin or eyes. If this happens inadvertently, which often does, quickly rinse the area thoroughly with tap water. Semi-paste strippers work well on most all surfaces but intricate or highly detailed pieces may require using the liquid version to reach tight areas.
Refinishing furniture with carved out areas and end grains will probably require additional effort as the paint or varnish tend to be absorbed rather than simply lying on top of the surface.
Stubborn surfaces may require a subsequent applications and removal.
Because stripper contains wax and not all gunk created by the old paint and varnish will be removed with your scrapper it is necessary to remove any residual or you will have problems with stain absorption or top coat adherence. Rinse well in mineral spirits or lacquer thinner (my choice) to rinse away remaining stripper and dissolve wax.
There is a water rinse-able stripper available but I don’t use it. Water is slow to dry. Mineral spirits and lacquer thinner evaporate very quickly and as a result do not “raise the grain” of the wood as much as water, due mostly to the drying time. Water causes the wood fibers get “split ends” just like human hair. This requires additional sanding and drying time before your next finishing step.
CHEMICAL FURNITURE REFINISHING DRYING TIME
The next step is varying degrees of sanding. If done properly only light sanding will be necessary. Sanding works on dry wood so typically I let the wood dry (in a non-humid environment) for 7-10 days.
To get a visual idea of all the steps in refinishing and a few easy wood projects be sure to go to my YouTube Channel to see:
“Chemical Strippers vs Heat Gun – Furniture Refinishing”
“Choosing the Right Grade Sandpaper for Your Woodworking Project”
“Botch-Free Wood Stain Application Technique”
“Bubble Free Polyurethane Application Technique”
“Fixing Polyurethane Bubbles, Puddles, Runs and Brush Marks”
“Building a Fishing Line Winder and Despooler for Under $25“