Back to basics! That design theory makes my head hurt… I have to glass several boards across a week at a time due to my limited time restraints so in the course of a week I have four ready to sand. The first has been sitting for 5 or six days waiting and the last is only a day old green. Is there a best time to sand? The week old one is definitely harder and the day old one is still pretty soft by comparrison. Are there any dangers to waiting too long as opposed to not long enough? Hell I can barely get the sealer dry and a quick buff on it before those little groms are frothin’at the mouth with their hands out and glaze in their eyes, bags on, motor runnin’ on their way to the beach…gimmeee…gimmeee, gimmeee… to check 'em out.
We try to sand ours within 12 hours. You’re right, they get too firm inthe following days. I’ve seen them get hard like ice and the usual sandpaper just dances on top of the hard hotcoat. Got to break those down with a heavier grit… Remember, these comments refer to a board that has been minimized technique/material-wise (high performance and grom boards). We try to BARELY sand into them. Normally starting with 150grit or finer, so timing does become important. If it is a big board that will get gloss then it doen’t really matter (“weave” showing is not as critical); just go the brutal grits and smoke the thing…
I usually start with 100 grit and go at it carefully. The grom boards are ultralight foam and 3 x 4 glass thin and tight! I have to be very careful and I still burn’em in a few places. I guess I have to get some 80 to attack the harder boards with on the first pass. Have to work on em when time permits so my waiting period is not totally controllable. Also I think sanding is everyone’s least favorite and most difficult step so it could be a bit of procrastination coming into play. I hate the thought of messing one up after all the work it took to get to that point. Hats off to all the production sanders out there! You have a noble part in the production line.
So basically at least 12 hours and 24 to 36 is probably optimum.
I agree with “sooner is softer”, and have found that around 24 hours there is a nice balance between sandability and keeping the weave from fraying a little on the lap. I’m talking about miniscule degrees of seperation, but having a greater impact on sanded finish boards that will not be glossed. I have also noticed that when using sanding resin as gloss on larger repairs on longboards that it takes a minimum of 3 days (no matter how hard I kick it) for the resin to be hard enough to get proper results when fine sanding before polishing.