Replies

1. 
   SgianDubh | Nov 06, 2004 08:12am | #1

   It's not an ideal base for pre-cat, Chuck. I'd make up a couple of 1 ft square test panels using the same shellac and same application procedure as you used on your bed-- cheap ply will do, or some veneered MDF.

   On the first panel spray the pre-cat you mention you're likely to use as normal. If there are problems you'll find out soon enough-- within minutes of applying the first coat probably.

   If you encounter problems, on the second panel, thin out the pre-cat about 20% polish to 80% lacquer thinner. Use the spray gun to lay down a spit coat. The thinner will evaporate fast leaving behind only a few solids. You'll probably find just 2 or three coats applied like this will allow the pre-cat to stick.

   Here's two further highly workable options.

   Apply a coat of dewaxed shellac over your waxy stuff-- easy solution.

   Strip what you've applied and start again-- shouldn't be necessary if you follow either of the suggestions above. In many ways I like best the application of a dewaxed shellac barrier, which can quickly and easily be sprayed on as you'll be doing for the pre-cat. Slainte.

   RJFurniture

1. 
   Chuck1033 | Nov 06, 2004 04:56pm | #2

   Dear Sqian; Thanks for the 2 suggestions.  Using dewaxed shellac, when it burns in doesn't it still leave wax on the surface?  That was my quandery about using that approach.  Interesting bio you have--congratulations.  Chuck

1. 
   SgianDubh | Nov 06, 2004 10:45pm | #3

   Chuck, I wouldn't expect you to have a problem with wax coming to the surface. True, the layer of dewaxed shellac sprayed on will cause the very outer molecules of the cured film below to soften allowing the two layers to bond.

   But the layer below won't dissolve to the point that it's completely liquid again, which would likely cause severe problems such as sags, curtains, runs, fat edges, etc., as if you'd sprayed a too heavy coat in the first place.

   Make up a test panel as I suggested before to see how it works.  Slainte.RJFurniture

1. 
   Chuck1033 | Nov 07, 2004 02:30am | #4

   Thanks, will do.  I'll let you know how it comes out. Chuck

2. 
   HowardAcheson | Nov 07, 2004 07:22am | #5

   The only finishes that should not be used over non-dewaxed shellac are oil based polyurethane varnish and waterborne finishes.  All other finishes and standard oil based varnish are fine over non-dewaxed shellac.

   Howie.........
1. 
   Chuck1033 | Nov 07, 2004 11:22am | #6

   Thanks Howie--I'm going to try precat lacquer.  I'll let you know how it goes.  Chuck.

1. 
   HowardAcheson | Nov 08, 2004 09:35pm | #7

   You didn't say it was "pre-cat" lacquer.  I'm not sure whether that finish can be used over shellac whether dewaxed or not.  I stay away from pre-cat because of the danger.

   I would recommend you directly contact the manufacturer and discuss it with them.Howie.........

1. 
   Chuck1033 | Nov 08, 2004 11:47pm | #8

   OK, WILL DO

2. 
   SgianDubh | Nov 09, 2004 03:15am | #9

   Pre-cat will go over dewaxed shellac without any problems I'm aware of Howie. I've done it quite a few times myself. I'm wary of spraying it over regular shellac, but that's only because of the wax in it. Slainte.RJFurniture

1. 
   HowardAcheson | Nov 09, 2004 03:50am | #10

   OK Richard, I'll file that info away.  As I said, have only used pre-cat lacquer once.  The local EPA requires that it be used by exhausting into some rather expensive scrubber filters if used within a certain number of feet of another building.Howie.........