When Things Go Wrong 8/14/2012 10:00:00 AM
Often a job is on a tight schedule when it hits the finishing room. So how do we feel when things go wrong, to the point where the finishing process is well underway and suddenly we realize we have to start over? But that’s not all. Now we’re faced with an additional messy, labor intensive step that must be completed before we’re back to where we started. That is, we have to strip the finish we just put on.
Several mishaps can bring us to this point. Perhaps the color somehow comes out too dark or too muddy. Maybe some defect such as bubbles or fisheye appears in the sealer or topcoat; or maybe it’s just the result of an accident.
Having been in the restoration/refinishing business for many years, I’ve had to strip furniture many times and it’s never much fun. There are techniques, however, that can make the process less horrible than it may first appear.
The first and most important factor in stripping a finish is safety. Not surprisingly, the chemicals involved are dangerous to your health. Don’t skimp on protective clothing or good ventilation. A respirator with chemical filters is a necessity even when you have adequate ventilation since you’ll be working close to the surface, where the fumes are the most intense. The most effective chemical commonly used in stripping is methylene chloride. It can burn your skin on contact and prolonged exposure can cause damage to your liver, amongst other things.
One crucial key to success is to take full advantage of the aggressiveness of the chemicals. Let them do the work. The most practical method of application for most of us is to use a natural bristle brush. Lay it on heavily and thoroughly, brushing it out with as few brush strokes as possible. Then let it sit. Thick finishes may absorb the remover and show dry spots. These will need additional paint remover applied. Again, lay it on thick without excessive brushing. Some finishes require a half hour or more to become fully dissolved. Test an area with a putty knife, being careful not to gouge the wood. Softened edges and rounded corners on the putty knife prevent gouges. If the finish is stiff, gooky and strongly resists the progress of the knife, the remover needs more time to work. When the knife can slide more freely, scrape the excess off the surface and catch the accumulated gunk in a shallow cardboard box or tray. This only works on flat surfaces. Putty knives aren’t much good on carvings and turnings.
The next step is to wash the surface clean by scrubbing with a combination of steel wool (usually no. 1 is adequate) and a solvent. A stiff brush can help with deep carvings or turnings. Methylene chloride can be washed off with water, but water may not be the best solvent since it will raise the grain. Also, if some spots of the finish are not completely dissolved, the water won’t help. A better option may be lacquer thinner. Again ventilation is important but now you’ll need to be concerned about flammability.
The final step is to wipe the surface dry with disposable rags. To achieve a clean, smooth surface, be sure to wipe each area dry before the solvent evaporates. If the surface shows spots that were missed, re-apply the paint remover to the whole section or surface (top, side, etc.) and repeat the process. Never leave paint remover sitting on part of a surface; you’ll run the risk of creating color variation. Don’t try to remove stubborn spots by excessive scrubbing or sanding. A properly stripped surface should need very little, if any, sanding. Substantial sanding is required only when stain needs to be removed from within the wood.
Never dispose of waste materials that are not completely dry. Methylene chloride and lacquer thinner are hazardous materials and should be treated as such.
One alternative to methylene chloride is N-Methylpyrrolidone. It’s somewhat less hazardous than methylene chloride but not completely benign. It’s also more expensive, slower, less effective, and it doesn’t dry readily. Undersides must be cleaned thoroughly or they will remain slimy.
Another type of paint remover is based on solvents found in lacquer thinner along with additives that slow evaporation. These removers are effective on shellac and lacquer finishes but not on more stubborn finishes such as conversion varnish.Using paint remover properly can help you make the best of a bad situation. Hopefully, you won’t need to repeat the process any time soon but when you do, you’ll be better prepared.