Replies

1. 
   Azeddie | Jun 13, 2002 08:59pm | #1

   I would , the varnish will gring back the shine anyhow

2. 
   gerry001 | Jun 13, 2002 10:12pm | #2

   I would lightly sand the surface primarily to remove any imperfections before applying the varnish. The amount of sanding depends on how smooth the current surface is. It will be much easier to smooth the shellac than the varnish.

   Gerry

3. 
   RLMillard | Jun 14, 2002 02:03pm | #3

   I would certainly sand back the shellac. I also use Rock Hard varnish for all my tops. I don’t know if it will cause a problem down the road, if you used standard shellac, but its wax content could lead to delamination of the varnish film. I would over coat the shellac with some dewaxed shellac. I am a big fan of the Rock Hard, but it is without a doubt the most difficult finishing material I have used. The drying time on the can must be Behlen’s idea of a joke, as it rarely dries dust free in less than 12 hours. They recommend 72-96 hours before rubbing out, and it actually should cure for 10-14 days (longer if you can). It also will show witness lines, so your better off to level sand after each coat, because any heave sanding will reveal that halo like effect of the witness lines which ruins the finish and forces you to apply another coat. Altogether I takes about a month to achieve a first class finish with Rock Hard varnish. Despite my less than positive description, there is nothing better than the Rock Hard, in terms of clarity, durability, and final appearance.

1. 
   tarobi | Jun 14, 2002 02:36pm | #4

   Thank you all for the very useful information.  I appreciate the advice.  Given that I am a novice and this is my first project I'm know wondering whether I should just use regular polyurethane. 

   Thank you again for taking time to reply!

   Allen

1. 
   RLMillard | Jun 14, 2002 08:40pm | #6

   I would go ahead and use the Rock Hard, the worst that can happen is you have to recoat it, if you don’t like the results. It is great looking stuff, worth the effort. As for the comment about the thinner, I don’t thin my varnish so I don’t know if regular thinner would work or not. I’m also not sure that dewaxed shellac is necessary, but I’d hate to find out the hard way, that it is.

2. 
   tarobi | Jun 14, 2002 07:25pm | #5

   Rob,

   FYI - they may be wrong but I wanted to let you know what a guy posted on another woodworking forum to the same question. 

   He said that Behlen's claim that you must use their thinner is incorrect - that regular spirits will work fine as with any varnish.  He also said there should be no adhesion problem  - the dewaxed shellac would only be a need for "poly" varnish - not standard varnish. 

   Again - he may be wrong but I wanted to let you know.

   Allen

1. 
   gerry001 | Jun 15, 2002 06:36am | #7

   A high wax content in shellac will prevent adhesion by water bourne poly. For any oil base finish, the solvent will dissove the wax. However, the adhesion will still be weaker than ti should be. Probably better for standard varnish, since it dries much-much slower than most poly. Also, the wax content in the shellac may vary many times over, so it may be better or worse than I've said here. Much easier to just use dewaxed shellac.

   Nearly any finish (for home use) can be applied over dewaxed shellac. The only recommended finish to apply over waxy shellac is wax.

   I agree on thinning the varnish with regular mineral spirits.

   Gerry

1. 
   sschefer | Jun 15, 2002 07:43am | #8

   Gerry, I totally agree. If you read the can's you'll find that all of them say not to apply over any waxed surface unless it has been completely stripped.Steve - in Northern California