godskin wrote:Is it a good idea to sand the tub lightly with 150/200 grain before the third stain ?
Yes you want to sand lightly with 320 or finer grade.
Also you can buy this pads kind of brillo pads and
buy the one for in between coats and you can use
000 steel wool as well. The only thing with steel
wool is if you are using like water based products
is not recommended because steel wool may be
left behind on the surface and rust with water based
products. For the most part when you dealing with
oil and waterbased finishes you want to always sand in
between coats to create a mechanical bond. When
using and applying several coats of either shellac
or lacquer is not really required to sand in between
coats because each coat melts into the finish and form
one coat. You see varnishes, enamels, and polys are
not like that each successive coat creates a layer
on top of the last one so you have to abrade the last
coat after it dries to create a mechanical bond for the
next coat to adhere to the last coat.
The only reason you may want to use a sanding
sealer and that is "de-waxed shellac" is when you
may have compatibility issues. For example like
going from an oil based finish or enamel to a lacquer
top coat. You see normally the solvent in lacquer may
be too hot or too aggressive to put on top of oil, enamel
or varnishes specially when not fully cured, they may
take month before they cure. So the lacquer may
ruin you previous coats so the solution to this is to
use dewaxed shellac (universal sanding sealer) in
between. Just a little finish 101 that is good to
know. I hope this helps.