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Sanding Sealer - What is it?

8.3K views 11 replies 8 participants last post by  derek willis  
#1 ·
A year, or so, ago I purchased several cans of Olympic Oil- and Water-based "Sanding Sealer" from Lowes during a inventory close-out sale. I've used the stuff on a few pieces and it appears to be similar to Deft brush-on lacquer, producing a soft (no protection), thick, self-leveling surface. The directions on the can aren't real specific, but seem to indicate that the sanding sealer should be applied after staining, but before a final top coat such as polyurethane. In any event, the product does yield a nice deep finish when used with a final coat of polyurethane.

That's all fine, but when I read previous posts on finishing, the discussions usually suggest a process where "sanding sealer" is applied prior to staining. Is that correct? I'm familiar with "pre-stain" conditioners (contents ???) for light and softwoods which help prevent un-even stain patterns, but these products have no build height and basically evaporate in 30 minutes after application.

In short, am I using the sanding sealer in the wrong way? Is it similar to lacquer? What is it?

Thanks

TTG
 
#2 ·
Sanding sealer is designed to help you get a level surface quickly. It fills in the tiny voids that wont show up until a top coat is applied. It also works like a stain prep because it seals the surface so you get a more even distribution of stain. Sanding sealer dries clear. If the exact tone of color is not critical you can use shelac and save some money, it will do the same job but will impart a slight tint.
 
#3 ·
In simpler terms a sealer or sanding sealer is a primer for clear finishes.

I have never had the super blond shellac change the color of the finish, especially since you sand over it. Super blond is darn near as clear as a water based finish.

I like shellac because it is compatible with EVERYTHING. I usually mix my own here in the shop.
 
#5 · (Edited)
I usually mix my own. Hock makes some, Rockler and woodcraft carry some. The most important thing is to get Dewaxed shellac which is shellac with no wax and only use Denatured Alcohol.

Go here and read the Shellac story and directions for use:

Hock Story of Shellac

Here is Rockler and woodcraft links for the flakes:

Rockler Brand Shellac Flakes from Rockler

Hock Shellac Flakes from Woodcraft

Zinsser makes ready made and is great but it is not as clear as a super blond, but good enough for 90% of everything you do. It comes in sealer and an Amber, a Garnett, a Clear and a Spray:

Zinnser Shellac Sealer

Zinnser Clear Shellac

Shellac Spray

Instructions on using Shellac from Zinnser

Any of these products are good, I stay away from the Zinnser Amber though.

What is nice about the flakes is you can mix any pound cut you like. Adding the alcohol you can make it thinner or thicker. After reading up on shellac you will understand what each lb cut or ratio of alcohol to flakes will do. Basically the sanding sealer is just diluted with more alcohol. You can also add tints to the Clear, Blond and Super Blond shellac to make almost any color you need too.

Tint dyes for water and alcohol based finishes

Shellac dissolves itself so adding it is not like adding Poly, Shellac actually melts into the previous coat. Shellac can also be truly buffed out(poly can not be) or French Polished for what I think is the best traditional finish there is. And of course you can wax over the shellac. A shellacked floor that is then waxed over is my favorite floor finish and arguably the best looking of any floor finish.

Shellac is not the strongest finish and for a table where alcoholic drinks will be placed it is not a good finish. But for 90% of your projects shellac will work. Using shellac as a sanding sealer is a no brainer for me as it is the only thing that is 100% compatible with any top coat, even poly.

French Polish(using shellac) is Arcane, but is a truly traditional and acceptable furniture reproduction or restoration finish:

Primer on French Polishing

FAQ on French Polishing

PS Don't forget to purchase the alcohol for the Flakes or to thin out the ready made Zinnser products, DENATURED alcohol ONLY!.

Did I mention you do not even need clean your brushes, if you forget to clean them just sit them in alcohol when you are ready to use them again and they work fine. I actually clean after use by just rinsing with a little alcohol then wrap in a zip lock bag and throw it in the fridge. I have pulled out brushes a year later and they worked great!
 
#12 ·
You can make your own Shellac with Shellac flakes and methylated spirit, that's how I make my Shellac for French polishing, I generally use Blonde de-waxed flakes, because they are very pale, once you have the basic Shellac you can dilute further to obtain Shellac Sanding Sealer, one or two coats of this will help your final finishing so very much easier, but don't forget to sand down before applying the final fiish.