I had a terrible disaster in the shop and need some help. I was putting a shellac finish on a piece. I ran out of denatured alcohol and bought some more. I couldn’t find the same brand so I used a brand named @#&*( Don’t really want to get sued) Denatured alcohol.”Contains methyl alcohol and other dispersants and flattening agents”.Let’s just say it was a white can with a purple lable. I had five coats on it. It had hardened for about 5 days since I’d put the last coat on.
I mixed up some flakes. It smelled odd, almost like it had linseed oil in it.It also gave me a headache. I used good Behlen’s brand orange shellac- 2lbs cut.
When I brushed it on it opacified the finish- not immediately but after a few minutes. It left brush marks everywhere. Three hours latter it had an oily sheen on it. When I wiped it with a cloth a yellow oily residue came off on the cloth. The entire finish was still cloudy- no sheen left at all- it had previously a beautiful deep glow.
This was to be the 6th coat of shellac on a piece I have >200 hours in.I need some advice as to what to do next. I sanded some of it down and tried some left over shellac with a different solvent. It looked better but still rather streaky.
I think I am going to have to rub it down with steel wool and another brand of denatured alcohol and then start over.Did I do something wrong? Has this happened to anyone else?
Frank
Replies
Frank. I'm rather stumped as to the cause of the oiliness you describe in your finish. Denatured alcohol is not oily, regardless of the brand, and shellac flakes do have varying amounts of wax in them depending upon their grade or refinement. The wax in the flakes can be allowed to settle in the mix and the clear (much reduced wax) liquid filtered off as you know. My best guess is that there is an impurity in one or both of the ingredients that you mixed. You only have two-- the shellac and the denatured alcohol, so the process of elimination should be fairly simple. You know that the denatured alcohol is a new can, but what about the shellac? You tried diluting the stuff in a different brand of alcohol, with somewhat better results, but is that too a new batch, or were you using those same flakes successfully (with the solvent [alcohol] you were using before) for the previous five coats? Apart from that, the only other reasonably conceivable source of contamination I can think of would be the mixing container(s) and the brush(es) you used. The last thing I can think of that might have affected your drying finish are the weather conditions, which if very humid could conceivably cause opacity, but I'd guess this is unlikely, and doesn't address the oiliness fault.
You'll probably end up having to strip the finish back. It might be safest to strip back to bare wood, but there's a couple of tricks I'd try before that. Try naphtha as a degreaser, and mineral spirits should remove a lot of the oil too. After that, and even though I can't ever recall using TSP (Tri Sodium Phosphate) on shellac, so I'm not sure what the results would be, you might try this stuff as a degreaser in an inconspicuous place to see what happens. (I've bought TSP at places like Home Depot, so it should be easy for you to find.) None of these suggestions address the brush mark issue, which may be related to whatever caused the oiliness. At worst you'll end up having to strip the lot if none of the tricks I've suggested work. But at least trying the naphtha and mineral spirits should do nothing to remove or damage the good coats below your faulty sixth coat.
Making a long distance diagnosis like this is always fraught with danger, especially with finishing problems, and I'm not the hottest finisher in the world, so take my opinions, suggestions and thoughts as just that. I could be wrong, and someone might have a better suggestion. Finishing problems are always frustrating, and I'm sorry to hear that you're having trouble. Hopefully you can sort it out and get the result you want in the end. Slainte, RJ.
You might try posting your question on Jeff Jewett's forum at his Homestead finishing website or by calling him. If you're not familiar with it, the forum is a place for folks to ask his advice about finishing topics. My experience has been that he's very generous in sharing his expertise and making recommendations.
Frank;
Sgian Dubh (RJ) brings up some good points about possible sources of contamination.
To repair the problem, I would sand the TOP off the finish to remove the last coat. I favor 3M fine sanding sponges for this type of work, though if you're more comfortable with sandpaper that will work fine also. I use this method whenever the last coat has "problems" that have to be corrected - it works with any finish that is "thick" enough to sand back without cutting through the underlying coloring.
All alcohols are not created equal - stick with the one(s) that give you good results. If you use a high quality alcohol with shellac, you will always get consistent results. Behlen and woodfinishingsupplies.com both sell a PURE alcohol that you can trust. Get rid of the batch of shellac that's causing problems - it won't get better. Personally, I'd do the same with the "@#&*" alcohol.
In response to the multitude of conflicting opinions on the subject of finishing, I've decided to include references for my posts. Here are some articles/references that relate to shellac. Some of the information targets your specific problem - how to fix it and how to avoid it in the future.
http://www.homesteadfinishing.com/ChoosingFinish.htm - "Choosing A Finish"
http://www.woodfinishsupply.com/ShellacFlake.html - "Shellac Flake"
http://www.shellac.net/information.html - "Shellac - The Woodworker's Pal"
http://www.shellac.net/faq.html - "Shellac FAQ's"
http://www.homesteadfinishing.com/shellac.htm - "Shellac - A Traditional Finish Still Yields Superb Results"
http://www.homesteadfinishing.com/shellac2.htm - "Padding Shellac"
http://www.milburnguitars.com/frenchpolish.html - "French Polishing (A Comprehensive Tutorial)"
http://www.wwforum.com/faqs_articles/alcohol.html - "Alcohols for Finishing"
http://www.shellac.net/brushes.html - "Brushes for Shellac"
Paul
F'burg, VA
Thanks all for your help. I think I figured things out.
I bought another can of the same brand denatured alcohol. It smelled entirely different and is crystal clear. The stuff that caused all the problems is amber and smells like a fishy linseed oil. Somebody must have played a little prank. In Sicily we deal with such sophomoric tricks with supportive counselling (One guy supports the culprit while the other guy counsels him on proper behavior). 200 hours in the piece and 10 in the finish- not very funny.
I am going to wipe everything down lightly with naptha and then sand the top layer with 320 grit (which should be a real pain) and put a few more coats of shellac on. I'll post a picture when done.
Gotta watch your step these days.
Frank
Ah jeeze Frank, I'm sorry to hear that. I was thinking mislabled can before but wasn't sure... when you said fishy smell, I read it almost immediately as raw linseed oil. That really sucks. I sure hope the piece survives.Steve - in Northern California
Folks,
The adulterant in the alcohol was, I believe, turpentine. I repaired the finish with naptha, sandpaper, steel wool and four more coats of shellac. I padded on the penultimate and last coats which almost gives it a French polished look.
Thanks to all for their advice and very good references.
Frank
For what it's worth ... I had
For what it's worth ... I had a similar issue a few years back and used Everclear (180 proof grain alcohol beverage) to clear the mess off and began again with fresh shellac. Everclear is not cheap, but in comparison to the time and effort that goes into a project, it can turn out to be a bargain. Any leftover can me used to mix with the shellac or imbibed. Your call.
Phillip Anthony
frank,
would you mind posting some photos of your work? if you did, then disregard this. my computer does not display all images posted.
thanks,
eef
paul,
great post and thanks for sharing those links. i am new to shellac and very much appreciate the information.
eef
How the h*ll did an eight year old thread pop up to the top of the pile, ha, ha. Slainte.
Richard,
It's the new,
Richard,
It's the new, "green" Knots-- renew, reuse, recycle.
Ray
Ah yes Ray. I'd forgotten
Ah yes Ray. I'd forgotten that aspect. Slainte.
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