Replies

1. 
   SteveSchoene | Jul 14, 2010 10:20pm | #1

   Sanding between coats of shellac is never needed to assure adhesion.  The reasons to sand are only if there are defects that you would like to eliminate before going on.  As with other finishes 320 grit is a good choice and the sanding scratches at that level should be eliminated by the next application of shellac.   Drying time varies with how many coats of shellac you already have applied.  After just a couple of coats it will seldom need more than 30 minutes drying time.  If you have a thicker shellac film you will have to wait longer.  If it powders it is ready to sand. 

   Remember that shellac doesn't need or want a thick coating like you might build with spar varnish.  It likes thin.  That doesn't mean that you can't apply quite a few coats if you expect to sand off much of it when filling pores or doing a thorough rub out process that includes flattening the surface. 

1. 
   Quickstep | Jul 14, 2010 11:12pm | #2

   Thanks, Steve.

   I started out sanding between every coat, but felt like I was sanding off everything I put on. Then I switched to sanding every other coat, but it seemed like the finish was getting too lumpy. I sort of felt like I was damned if I did and damned if I didn't. Ordinarily, I've done one coat, sanded lightly followed by another coat (maybe two) followed by steel wool and wax. In this case however, I need to build up enough to be able to sand it dead level to show off the ebony and inlay below.

2. 
   Yersmay1 | Jul 15, 2010 09:01am | #3

   Here is a link to a YouTube tutorial on rubbing out shellac.  I think it will be really helpful.

   http://www.youtube.com/watch?v=BPtGu5scc7A

3. 
   DonStephan | Jul 15, 2010 08:11pm | #4

   Perhaps I missed how the shellac is being applied.  If padding, the individual layers or coats are infinitesimally thin, and sanding shouldn't be needed.  Spraying or brushing 1# cut  will build faster, but unless lots of drips and runs still should need minimal sanding. 

   Could you provide some more info on how the shellac is being applied, what grit is being used, the type of sandpaper, and whether there is a backer pad?  I'm especially puzzled that sanding leaves the surface lumpy.

4. 
   Quickstep | Jul 17, 2010 08:09am | #5

   I'm spraying 2lb cut shellac and sanding between coats with 320 grit paper. Despite the fact that I'm spraying, the finished surface has a small number of pock marks. When I try to erradicate them, I end up sanding through. If I spray multiple coats before sanding, I simply seem to increas the number of pock marks I need to sand out before proceeding.

1. 
   DonStephan | Jul 18, 2010 02:22pm | #6

   Pock marks suggests silicone contamination.  A few more questions.  Are you spraying waxed or dewaxed shellac, did you mix your own flakes and alcohol or purchase dissolved shellac, and how old is it?  Are you spraying on new material or old?  Could you, on a new piece of scrap, apply on half the surface some of the shellac with a new clean brush and spray the other half as you did on the problem piece. 

   If the problem is contamination, it could be on the surface or perhaps in the spray equipment, I think.

5. 
   Quickstep | Jul 19, 2010 03:57pm | #7

   I think I may have figured out what was going on. I was spraying shellac from a rattle can. I think  what was happening was that the propellant was getting below under the shellac, then, because it's hot here, the bubble was making it to the surface just as the shellac was begining to harden. I've switched to an automotive type HVLP conversion gun and I'm not experiencing the problem.

1. 
   DonStephan | Jul 19, 2010 07:31pm | #8

   thanks for the followup

   Thanks for following up with your explanation.  I wouldn't have guessed that.  Hope we'll add it to our collective memory for the next instance.