Old varnish that cannot be recoated must be completely removed. I use a chemical stripper or a heat gun to remove it, then sand. If you leave the old varnish, it will look bright yellow underneath the new varnish, so be very thorough when removing old varnish.
If you are just recoating existing varnish, clean thoroughly and sand lightly with fine sandpaper. When building up coats of varnish, keep sanding to a minimum and use 220 sandpaper or higher. Always keep the varnish area as free of dust as possible. Each speck of dust that finds its way into wet varnish seems to turn into a boulder when the varnish has dried, and you cannot sand it out without losing the entire coat of varnish in that area.
|Grab Rails Glowing|