Sanding sealer vs filler

[Steve Sawyer]

Obviously open-pored woods like mahogany, oak, ash etc. need to be grain-filled if you want a smooth glossy finish. However, would a sanding sealer be appropriate for a close-grained wood without open pores like alder, poplar, cherry etc. (I'm working toward a painted finish, so the filler/sealer doesn't have to be clear)?

[Barry Daniels]

Sanding sealer would work but you don't really need it. Sanding sealer is intended for guys finishing lots of furniture or cabinets with massive surface area and it makes sanding much quicker. A guitar is much smaller in comparison so you can just apply your lacquer directly on the wood. The first couple coats of lacquer can be thinned out some and this serves as your sealer.

[Clay Schaeffer]

Sanding sealer can give you a quick build up of finish that can be easily sanded smooth at the expense of some adhesion of the top coat. On a cabinet that isn't touched much it doesn't make much difference. On an item that is constantly handled (like a guitar) the slightly better adhesion of self sealing with the top coat might be a plus.

[Steve Sawyer]

Thanks. I was planning on two or three coats of some kind of primer or sealer, sanding back after each coat, then shellac, sanding and then start applying the lacquer.

Sounds like overkill, huh?

[Barry Daniels]

Sounds like a disaster waiting to happen.

[Steve Sawyer]

Sounds like a disaster waiting to happen.

Okay - I consider myself as having been warned!!

Just sand the hell out of it, then start applying lacquer. Got it!

[Barry Daniels]

Yep, keep it simple. Anytime you start layering different products you risk incompatibility. Of course, shellac is compatible with most everything but there are a few exceptions.

[Clay Schaeffer]

http://www.woodshopnews.com/columns-blo ... -just-hype

An interesting article on shellac by Bob Flexner.
Although not mentioned in the article, shellac can cause some adhesion issues when used as a sealer. I only use shellac under finishes when I am trying to create a "barrier" between the finish and what is under it.

[Steve Sawyer]

Thanks, Clay - that's really interesting.

I note that there have been comments elsewhere on this forum re folks using shellac over epoxy filler before applying WB lacquers. I wonder if that (to your point) is a suitable application for shellac in a new-finish context.

By the way - I ran across another article somewhere recently that mentioned potential adhesion problems from use of sanding sealers, confirming some of the advice being offered here.

[Dan Smith]

I use Behlen vinyl sealer under Behlen Nitro Lacquer.
Never had a problem with it.

[Steve Sawyer]

I use Behlen vinyl sealer under Behlen Nitro Lacquer.
Never had a problem with it.

Well, that certainly looks like a successful finish. What did you use for a filler or does the Vinyl Sealer build enough to do that as well?

[Chris Richards]

I tend to stick to cellulose finishes, I can't imagine getting a good finish on ash without using a grain filler as the pores are so deep, generally I use a clear grain filler, once that is sanded back I spray one coat of sanding sealer which again I sand back, it's so much easier to sand than any primer I've used, I then spray a dust coat of the colour and block sand which shows up any imperfections, once they're fixed I spray the colour very lightly sand then clear coat...

Usually I'm not one for loads of coats, usually finishing off with two or three coats of clear.

[Steve Sawyer]

I tend to stick to cellulose finishes, I can't imagine getting a good finish on ash without using a grain filler as the pores are so deep, generally I use a clear grain filler, once that is sanded back I spray one coat of sanding sealer which again I sand back, it's so much easier to sand than any primer I've used, I then spray a dust coat of the colour and block sand which shows up any imperfections, once they're fixed I spray the colour very lightly sand then clear coat...

Usually I'm not one for loads of coats, usually finishing off with two or three coats of clear.

Thanks, Chris. I'm expecting to do this with nitrocellulose, so I'm interested in your schedule. Above, I've been advised to NOT use any kind of filler or sealer. My body is alder, so I can see that I don't really need a filler, but something about not using any primer at all makes me a little twitchy. Even if it's not needed from an adhesion standpoint, making sure that I have a perfect surface, with minimal imperfections seems to argue (as you do) for a prime-and-sandback. I certainly don't want to cause any adhesion problems, but I'd also like to minimize the corrections needed after I start with the color. To your point about many coats, it would seem that shooting lacquer on bare wood will require more coats to build.

[Chris Richards]

Hi Steve...

For some reason I had my mind fixated on transparent blonde or natural finishes!... Yes I do use white cellulose primer/filler as a bass for colour, white isn't the best colour for spotting imperfections so I do "dust" over the primer/filler with a dark colour and block sand then any dents are easily spotted and if I can't sand them out I use a cellulose stopper. I avoid any significant sanding to the colour coat as it's a real pain to sand as it clogs up sand paper really quickly and I have a real aversion to wet sanding...Really I'm only looking to de-nib the colour before spraying clear coat.

I would be very nervous about using dissimilar products on the same finish but I hasten to add that I've never tried.

[Dan Smith]

I use Behlen vinyl sealer under Behlen Nitro Lacquer.
Never had a problem with it.

Well, that certainly looks like a successful finish. What did you use for a filler or does the Vinyl Sealer build enough to do that as well?

Steve, I used shellac and wood dust as a filler.
Dan

[Todd Stock]

Epoxy filler under vinyl sealer under nitro works under clears and colors for me. Will use epoxy or shellac on woods that do not need pore filler where it pops the grain. Also have been working with Endure-Var WB for necks...experimenting with epoxy pore fill under the Enduro-Var versus extra coats to fill pores...both work. West 105/207, but testing both SilverTip and MAS Low Viscosity for minimum color and resistance to long-term shrinkage.