Builders' Forum Archives
sigh- If you are glassing
Posted by Charlie Jones on Mar 20, 2005
and you are sanding prior to putting on the glass, you are wasting your time sanding to more than about 150.
In fact on the boats I build, I don't allow sandpaper to touch the plywood, except for where absolutely needed, in places like fills and scarfs, before glassing. Once I roll on the first coat of resin, I then do a VERY fast run over with an ROS and 100 grit, to knock off any nibs, etc. I also do a quick scraping if needed. On a recently launched 22 footer, sanding the hull pre glass took about 15 minutes TOTAL.
The resin you use to stick the glass on will fill any small scratches and you'll NEVER see them once the glass is on. Plus sanding with finer than about 150 runs the risk of burnishing the surface and actually decreasing your adhesion.
AFTER it's glassed and the fill coats are on, THEN is the time to do the sanding with fine grits, to get it ready for varnish. Not before.
In Response to: sand paper grit by Patrick Forrester on Mar 17, 2005