"Sanding sealer" before or after sanding?

[Bombarde16]

OK, we all know that sanding sealer is nothing more than a thin cut of shellac which a.) does a great job controlling blotchiness and b.) it can serve as a topcoat or even standalone finish all on its own. But what about using it as the name implies? i.e. before sanding.

I tried this on a set of panels and made the following observations: It helped in spots of tearout where the router (1/4" roundover) hit a grain reversal and left some nubs sticking up. Having those nubs soaked in hardened shellac made them cut a little cleaner. But it also gummed up the sandpaper like nobody's business.

[dwacker]

If its gumming up your sand paper thin it. Bulls eye right out of the can is to thick for my taste. I rough sand then spray a wash coat then final sand.

Don

[CessnaPilotBarry]

Not all sanding sealer is shellac, but shellac may be the most universal version.

I have sealers of various formulas, including water base, for various purposes. Often, the non-shellac versions sand better than shellac, as they use harder resins that fracture more easily into dust, not gum. Shellac based sealers can also get gummy with age.

A good sanding sealer does make wood easier and faster to sand, as you've discovered.

[AceHoleInOne]

Next time run your panel about an 1/8 wider. Run your round-over bit. Then go back to the table saw and skim about a 1/16 off (half a blade) the entire panel. Then re-route the panel. Should take care of any tear-out you may be having.

They do have commercial wood "stabilizer" does what your are describing. But its just another product that really isn't necessary...$$$... to handle chip-out. Sometimes just wetting the wood with water or mineral spirits can help that too.