Expert: Greg Scholl - 6/30/2009

Question
QUESTION: I have been refinishing my kitchen cabinets and this is the third time I have come across this issue (the other times with the same type of project)  There are whitish marks/spots on the edges of the cabinet doors mainly, that I can scrape off with my fingernail, but can't seem to clean off with anything.  I am totally baffled by this.  It doesn't make sense to me that something I can scrape off, I can't clean off.  TSP, Vinegar, mineral spirits, lacquer thinner....I can't remember what else I have tried, but it is driving me nuts.  Please help.  There must be an easy explanation - surely.

ANSWER: Hi Stephanie, please give me some more info about stains, finishes you are using.- thanks- Greg

---------- FOLLOW-UP ----------

QUESTION: Greg,  I do not know what I the stain that is on the cabinets already is.  I have stripped some cabinets with paint stripper - or different types.  I have sanded the flat surfaces of my cabinets and there is not a problem there.  It is the areas that still have the finish on the from when we bought the house (3 years ago - don;t know how recently they were touched up) a very dark stain - probably with shellac over them.  Those are the areas I am having trouble cleaning off.  So I haven't done anything to those areas...I am going to leave them a dark stain and will poly (satin) the flat sanded areas. So it will basically have a glazed edge look.  No sanded area that I have already finished had a problem - but I have don't nothing to the edges, thus far.  Sorry that this is probably not much help.  I did take a cabinet to a professional finished and he stripped it in a tub - it did not take it back to the original wood - or take all the stain out of the wood - but the piece he did that too does not have any white spots on it - then again it was a high cabinet across the room from the main sink, stove, etc areas.   Sanded cabinets with a 80 girt orbital and then a 120 grit orbital and 0000 steel wool, mineral spirits to remove dust and do steel wool and tack cloth between poly coats.

Thanks STef

Answer
Hi Stef, The finish on your cabinets is almost certainly a catalyzed lacquer or varnish, over various sealer, stains and toners, MUCH tougher and harder to remove than shellac (or anything else for that matter),as your Pro finisher verified,if he was unable to get it off completely. These high tech finishes represent state of the art coatings technology that's formulated to be tough, durable, and good looking with almost zero maintenance for 20 years or more in a harsh environment like a kitchen or bathroom, and using polyurethane over this type of finish is not recommended. The areas that you've sanded that aggressively are most likely down to the bare wood, so obviously those areas can be poly'd. But you will end up with an odd look for sure with dark edges, and panel edges, and a bright, natural flat panel area. I'm still not clear on where the white spots are, and when they are appearing...it sounds like they are dried Poly, which will not be affected by any of the things you listed in your post (TSP, Lac Thinner, Mineral Spirits, etc). Wet Polyurethane can be affected by things like stain that's not fully dried, stripper residue, etc., that will cause it to turn whitish, or even bluish- white, and it will still dry hard, and then the only thing that will remove it is stripper, or a physical removal like scraping, sanding or chipping. It's quite common for a finishing material like urethanes, Varnishes,Catalyzed lacquers, epoxies, etc. Once the material has cured, it's almost impervious to solvents, cleaners, etc. that's kind of the whole point of a good, durable finishing material. I must tell you that sanding any finish down in order to refinish is not a good idea, it really needs to be stripped properly, down to bare wood as proper prep for applying a new finish. Also poly, (especially a consumer grade product like Minwax), will not be as durable or long lasting as the factory applied finish, and will likely not stick well to any catalyzed product. Could these white spots be splatter from a recent ceiling paint job? Many times painters don't bother to mask everything, and just roll a ceiling thinking that they're not getting paint on anything, when in fact they're leaving little dots of paint all over the place. ....dried paint would also not be affected by the things you listed, but would be by the proper solvent, like "Oops" or "Goof Off" which are dried paint removers.........