Replies

1. 
   SteveSchoene | Jul 25, 2007 08:53pm | #1

   To help you get a useful response you should give some more details.  What lb. cut shellac are you using.  What kind of shellac is it?  What are the environmental conditions--temperature and humidity?  What kind of spray system? 

1. 
   furndr | Jul 26, 2007 01:40am | #2

   I'm using a 3 lb cut (right out of the Zinsser can).  The humidity level is high today - probably 90%. I'm using a Devilbiss HVLP gun.

   I'm refinishing a  mahogany pedestal table. I put on a wash coat of shellac, filled the pores and put on a top sealer, also a wash coat (about a   1 12 lb cut). I then sanded lightly and  sprayed on a couple of coats of 3 lb cut. I then block sanded, and because some of the pores weren't filled, sprayed another couple of coats. Up to this point I had no trouble. After rubbing out those coats I sprayed on a couple more coats. That's when the trouble started - orange peel, blushing and the passes not blending.   

   Thanks for the response! 

1. 
   Ronaway | Jul 27, 2007 03:59pm | #3

   fundr,I never spray 3lb shellac, 3 lb cut is prone to window paning and orange peel. It's really too much finish at one time. If you cut the shellac back to 2 lb, then you can use it for the wash coat and additional coats, but give it time to completely off gas before appying additional finish especially on humid days. You may be trapping a lot of solvent in the subsequent coats and this would be especially true if the later coats were 3 lb cut. The blushing is probably due to the fact that the earlier coats are still trying to give off solvent and you've trapped that action under a heavy coat of 3 lb cut.I typically appy 2 coats of a 2 lb cut as a sealer and then wait till the next day to sand and apply additional finish. If the air is particularly dry that day then I might be able to sand that evening and apply another coat. But I always stay with nothing heavier than a 2 lb cut.The good news is that this is shellac and if you have to strip it off and start over then it is actually quite an easy task to accomplish.I have found that I tend to have more problems with premixed shellac than with shellac that I mix myself. I don't know what is included in premixed shellac to extend the shelf life, but I suspect that component may be part of the issue. The material I mix myself tends to laydown better in my experience.Ron BreseIf you're too open minded your brains will fall out.

1. 
   furndr | Jul 28, 2007 03:03pm | #4

   Thanks for the useful tips. I also called the Zinsser service line and they agreed with you that I should spray nothing heavier than a 2 pound cut.

   Where do you buy your shellac flakes? Also, is Home Depot denatured alcohol good enough for the solvent?

   Thanks.

   Dan

1. 
   Ronaway | Jul 28, 2007 10:54pm | #5

   furndr,I buy my flakes from Jeff Jewitt at Homestead finishing, and I've not had problems with the denatured alcohol from the BORG.RonIf you're too open minded your brains will fall out.

2. 
   furndr | Jul 29, 2007 05:43pm | #6

   Thanks!

3. 
   Ronaway | Jul 29, 2007 06:38pm | #7

   I'm glad I was able to help.Ron Bresehttp://www.breseplane.comIf you're too open minded your brains will fall out.

   Edited 7/29/2007 11:38 am ET by Ronaway

2. 
   amazon | Aug 04, 2007 05:00am | #8

   Agreed.I typically will max out with a 2LB cut, never more. Usually I spray 1LB cut. I find I can sand this out in 90min or 120. Probably I could sand it out in less than an hour, but I'm not in a rush. No reason to wait longer than 2 hours.I, too, buy mine from Homestead. Premixing their product just gives a better finish. Better quality? I'm guessing so.

2. 
   BruceT999 | Aug 05, 2007 12:19am | #9

   Ronaway has given you good advice about using a thinner cut, but I would quibble with the reason stated for blushing. Blushing is not going to be from solvent entrapment, since the only solvent is alcohol, which will find its way out. Blushing is more likely to be caused by water vapor that gets trapped in the film - either from high humidity or from wet air supplied to the gun. 3lb cut, after evaporative losses during atomization, probably gets to the wood surface at more like 3 1/2 to 4lb, so the film won't stay open long enough for good flow or to release water vapor. Incidentally, ethanol stored for extended periods in a humid environment in a large, partly full container, can absorb quite a bit of water from the air.
   BruceT

1. 
   furndr | Aug 05, 2007 06:17pm | #10

   Amazon & Bruce,

   Thanks to you both for the great tips!

    I do live in a very humid area, although I have a dehumidifier in my shop. How do I keep my alcohol free of water? 

   Dan

    

1. 
   BruceT999 | Aug 05, 2007 08:07pm | #11

   Water absorption into alcohol depends on:
   water content of the air
   surface area in the container for air/alcohol contact
   volume of air in container
   timeYour dehumidifier is reducing water content of the air already.
   Fast turnover reduces time factor.
   Smaller containers kept full limits surface area and air volume. So does topping off a larger container.
   BruceT

2. 
   frenchy | Aug 06, 2007 02:28am | #12

   furndr,

    I use overly thinned shellac because even if you have moisture contaminated alcohol there is enough alcohol present to compensate.  Excess alcohol all evaporates leaving you with the correct amount of shellac..