Salvaging a Bad Shellac Job
When a customer's efforts at tinted shellac finishing go haywire, how can a pro help? Here's advice on approaches to a fix. July 29, 2007
I run an exotic wood supply and custom cabinet company and do the finishing, so I have some experience, but I've got a sticky one. One of our customers purchased some maple, milled to bead board, crown, etc. The problem is he came in yesterday and said he had coated the maple with some tinted shellac, then tried to go over it with some clear but couldn't get rid of the brush strokes. After telling him he should've had us spray everything, we discussed the solutions. He has some columns that are very tall and hard to eliminate overlap, etc. I was concerned that poly would take too long to dry and eat into the shellac, causing an alligator finish. Do you think sanding smooth the clear shellac, then applying a thinned clear lacquer would work, or what would you suggest? It's inside a lived-in residence, so spraying anything is out of the question.
From contributor J:
Shellac re-dissolves easily; you can soak a rag in solvent alcohol and just wipe the stuff off. Also, it's much easier to apply shellac if it's done in several thinned coats rather than a couple of thick ones. You can dilute shellac in alcohol to whatever cut you find easiest to work with, without harming the integrity of the finish.
From the original questioner:
Thanks for the response, however, the problem is that the homeowner spent three weeks searching the finish color she wanted and the first two coats were tinted. He says she was unable to find any other color with stains of any kind. I kind of think he was looking for an easy way out. But, he's a good customer of ours so I really wanted to try and provide him with some solution to be able to leave the color coats on there. He said he thinned some clear shellac a lot. I thought that thinned lacquer would lay down better, yet dry fast enough not to destroy the colored shellac. Any other ideas out there other than removal of the existing shellac?
From contributor C:
Using the alcohol as suggested is the best way to handle the situation. The big difference is this - apply the alcohol to a pad such as used in French polishing, in long strokes. The alcohol pad will slowly soften the finish. Use a delicate touch when you start out and increase pressure as you go and the pad becomes dryer. Add more alcohol as you proceed and continue until you have the brush marks smoothed out as much as possible. Your rag will pick up color as you go along. This is normal, just make sure the pad is not so wet as to remove the entire finish or lighten the color in random areas. After you have smoothed the brush marks out, then let dry and apply a coat of either nitro or acrylic sanding sealer, let dry, and sand with 320 no fill. A second coat might be necessary; if so, repeat procedure. After that, apply a nitro on nitro or ac on ac in gloss and touch up tone any light areas with toner to match.
By then your finish should look very smooth and uniform and you can fine sand and top coat to the preferred sheen the customer wants. Shellac is totally compatible with nitro and shellac, but as mentioned should not be built up with more than one or two 2lb. cut coats because of its brittleness.
If by chance the finish that's now on there is a very thick coating it could cause premature cracking, etc. It will be up to the customer to decide if he desires you to attempt it or not. Make sure you let him make the decision and that you get paid for your attempt and that there is no guarantee. Do one small piece or area to show him what the finished product is going to look like and have him sign and approve it to cover yourself.
From contributor B:
I agree with contributor C, but I would rather not use any coat after the shellac. Only thin layer of varnish if you want to keep safe with that finish, because shellac is sensitive with other coats. Guarantee no crack on it. Try it on a piece of wood.