Dull Haze Problem when Cleaning Lacquer with Naphtha
A finisher gets advice on why he's getting a dull, cloudy look an a nitrocellulose finish after using naphtha to clean the surface. February 15, 2009
Question
I've been trying to clean some old nitrocellulose lacquer finishes and saw the suggestion here and on many other websites to use naphtha. After using it, I notice that after it evaporates, the finish is left dull, and hazy and gray in sports. If I hit it with spray lacquer or padding lacquer, the finish looks fine again. What is going on and is there something else I can do to bring the finish back other than top coating with lacquer?
Forum Responses
(Finishing Forum)
From contributor G:
What kind of naptha are you using? How sure are you that the finishes are N/C? If mineral spirits is attacking it, it may be old varnish. Try starting with a less aggressive cleaner - like Dawn in warm water and a soft rag.
From contributor R:
Make sure you are using VM&P Naptha and not the High Flash Naptha. I once cleaned a top with the High Flash Naptha from Sherwin Williams and it was so hot of a material it darn near stripped the coating off instead of just cleaning it. If you are stuck with the High Flash stuff cut it with some Paint Thinners/Mineral Spirits to lessen the bite.
From the original questioner:
In reply to the two answers, (1) the finish definitely is nitrocellulose and (2) I already am using VM&P. The VM&P had the same dulling effect on a newly refinished drawer front that had been rubbed out to a gloss finish using a Mohawk "Finisher's Choice" nitrocellulose aerosol.
From contributor R:
To the original questioner: are you just using a cotton rag to apply the Naptha or something more aggressive?
From the original questioner:
I'm just using a piece of trace cloth (finely woven cotton cloth used for French polishing).
From contributor R:
I’ve never heard of Naptha attacking a Nitro finish or for that matter a Varnish finish. Try a new batch of Naptha if you can. Maybe the can you’re using now got contaminated with a hotter solvent. It could be one of your finishers mistakenly poured off some L/T or Acetone into the Naptha can.
From contributor S:
Naptha can at times leave behind a hazy residue. Try a very quick swipe with a rag just slightly damp with ethanol or denatured alcohol and it might solve your problem. Otherwise, your haziness grey could also be water soluble dirt (schmutz) that the naptha is messing with but won't remove.
If the alcohol doesn't work then try cleaning the coating with a mild solution of ivory soap or even very dilute Murphy’s Oil then rinse very well with distilled water. Again, a final swipe with alcohol should clear up any blushing or residuals left behind.
