Replies

1. 
   Pondfish | Oct 19, 2004 04:31am | #1

   Is their any finish under the lacquer?  Or are you applying lacquer to raw wood?  It's best to use a sealer first.  Also, are you brushing or spraying? If brushing, be sure you don't wipe the brush on the edge of the can.  This makes bubbles.

   Paul

1. 
   nvwoody | Oct 19, 2004 05:02am | #2

   I'm brushing and yes I used shallac as a sealer, but with no side can wipeing with the brush , so  how do I fix the bubbles

1. 
   Pondfish | Oct 19, 2004 01:44pm | #4

   I would sand it down and reapply with a good brush. I use unthinned Deft brushing lacquer and I don't get bubbles.  As the other poster mentioned, stay out of the sun to ensure the lacquer doesn't dry to quicky.  I buff out the finish using Abralon disks, or maybe some 320 grit paper to get any bad brush marks. 

   I assume you used a dewaxed shellac (very important) when you sealed it.  Zinsser bullseye is not dewaxed and will cause adhesion problems, but I don't know if it could cause bubbles from forming. 

1. 
   HowardAcheson | Oct 22, 2004 12:50am | #7

   Dewaxed shellac is not necessary under lacquer. The only places where it is important is under oil based polyurethane varnish and under waterborne finishes.I have sprayed lacquer over standard shellac for years. Standard shellac was all we used in the shop I was involved with. We used it instead of sanding sealer under all our lacquer finishes. We did some rather extensive adhesion tests for the finishes we used on a line of semi-custom furniture we made for an interior designer. There was never an adhesion problem with lacquer over standard shellac.While I have never used brushing lacquer, most bubbles result from brushing technique. For shellac and varnish, the technique is to flow on the material with long, slow strokes and minimal back and forth brushing. Maybe this the the technique is the one that must be used with brushing lacquer too.Howie.........

2. 
   notDusty | Oct 19, 2004 08:05am | #3

                    jer,

           Well assuming this finish is on raw wood , it may be too thick a coat or possibly not thinned properly or the drying cycle maybe the problem . An example is drying a lacquer finish in the sun , bubbles occur as the finish dries uneven . A possible cure may be try a wet coat of Lacquer thinner over the entire surface, it may melt the bubbles . A good sanding with @ 220 then re coat with Lacquer , this method works when spraying the finish .

                        good   luck        dusty

3. 
   CharlieP | Oct 20, 2004 08:37pm | #5

   Although I spray lacquer rather than brush, occasionally I get bubbles if I get too thick a coat, especially in the sun or hot weather. 

   Lacquer contains a lot of solvents that have to evaporate - it is not a curing process like varnish.  If the surface hardens before the lower layer finishes evaporation, you get bubbles.

   Once you have bubbles, you can break the top of the bubbles, but you still have a very uneven layer of finish.  Putting another layer of lacquer on top doesn't smooth the finish (short of maybe dozens of coats).  So you have two options - sand the lacquer off, or use solvent (lacquer thinner). 

   The technique I usually follow is to wipe the area with a very clean rag wet with lacquer thinner.  It softens the lacquer and spreads it (but none too smooth).  I don't try to remove the lacquer, just spread it around.  The result will be pretty rough, but no bubble holes (that seem to be 6 inches deep if you just sand them).  I then sand the dried smeared lacquer smooth - probably only 1/3 as much sanding as if I had tried to remove the bubbles only by sanding.  Since each layer of lacquer (and the solvent) dissolve into the previous layers, this process will remove a lot of your work, so you will have to apply additional coats to replace the lacquer you removed with the rag and sanding. 

   I would not apply a different finish over the lacquer. 

   ________________________
   Charlie Plesums  Austin, Texas
   http://www.plesums.com/wood

4. 
   KeithNewton | Oct 21, 2004 04:38am | #6

   If you can see that the bubbles are coming from or forming over a pore in the cells of the wood, it may be due to air within the wood expanding due to a rise in temperature of the wood. So don't take cool wood and coat it with a finish then put under the hot lights. It is better to warm the wood first, then finish, and then let it dry on the cool-down.
   With a good magnifying glass, it is easy to tell if this is your problem.