Replies

1. 
   Danford_C._Jennings | Oct 15, 2001 08:54pm | #1

   *
   Jerry,

   No using a sanding sealer is not necessary. But, you should sand between each coat of poly. Yes use a filler for the nail holes, I use "Color Putty" applied before the last coat. FWIW.

   Dano

1. 
   Howard_Acheson | Oct 20, 2001 07:18pm | #2

   *To second Dano, sanding sealer in not necessary and should never be used under polyurethane varnish. The stearates cause reduced adhesion.

1. 
   Charlie_Frnka | Oct 20, 2001 09:48pm | #3

   *i sanding sealer in not necessary and should never be used under polyurethane varnishNot to disagree, but I'm doing a job right now where the client's specs are "stain, 1 coat of sanding sealer, and 2 coats of polyurethane." I'm through with 1 coat of poly on the cabinet doors after stain and a coat of "polyurethane sanding sealer" (it says on the can) and they're as smooth as a baby's butt.Charlie

1. 
   Howard_Acheson | Oct 21, 2001 07:44pm | #4

   *>>"polyurethane sanding sealer"Although I didn't say it, I was referring to the normal lacquer based sanding sealer. If you are using a product made specifically for use under poly varnish it is probably OK.Here is my diabribe regarding sanding sealer. It will probably liven up the discussion.It is my opinion that using a sanding sealer sacrifices quality for expediency. Sanding sealer is used simply because it is fast and easy to sand. It contains a zinc stearate soap that sands like a jewel. Most are lacquer based so it dries fast and they can get to that final sanding sooner. However, adding the stearate to the sealer coat provides a very weak base. While one could use the finest finish ever made as the final finish it will never be better than the base it is on. One thing it does not do is "seal the wood", whatever that means. A shop I was involved with manufactured a line of semi-custom and custom designer furniture directly under the direction of the designer. We sub-contracted the finishing to a professional finishing shop that we chose after visiting 12-15 shops in a 300 mile radius. None would use sanding sealer and our specs specifically forbid it based on the tests performed by the designer firm. There are standard tests for adherence and you could easily see the decreased adherence associated with sanding sealer containing stearates. This was very pronounced when using polyurethane varnish which has low adherence anyway so never use a stearate based sanding sealer under poly varnish.Lacquer based sanding sealers are primarily used by high production furniture companies where time is money. They do not experience adhesion problems as they use lacquer finishes, not polyurethane varnishes. Things get even worse with multiple coats of sanding sealer. Now you have a very soft finish underneath a hard surface. This will cause cracking and crazing when the surface is dinged. If the finishing product requires a sealer coat (sealer is different than a sanding sealer) it will call for it in the directions. Generally, the sealer is a thinned coat of the final finish. Sanding sealer is just not needed.

1. 
   Sgian_Dubh | Oct 22, 2001 05:17am | #5

   *No livening up from me Howard, for every single thing you said is just about spot on. Slainte. RJ.

2. 
   David_Osborn | Oct 25, 2001 02:13pm | #6

   *I would not use sanding sealers in potentially wet areas. Pre-catalised lacquers, with which s/sealers are normally used are not much good for situations that are likely to be damp. If you can use spraying then acid catalysed lacquers which have a much higher build and do not need any undercoat,are by far the best finishes for utility-room type furniture, kitchens, bathrooms etc , and can also give an excellent finish on more prestigious projects. Polyuethanes are not easy to use, and I certainly would not consider spraying them. They should be applied direct to the wood possibly with some thinning for the first coat, with a brush or rubber.As for your nail holes perhaps you should have filled these before staining.Your only option now is to use a wax stick after finishing.