Using West Systems. how much to grind old fiberglass? If I am grinding roving do you make it perfectly flat with 80 grit? Anyone use the Norton wire wheel?
Thanks

Is it an epoxy boat to begin with??

No not expoxy.

Any special reason your using west instead if say VE?

No. I just know of WS. I am grinding now and want to get the maximum adhesion, but no one has any pictures on the internet of grinding Glass.

What are you doing exactly?

maximum adhesion is with 36 grit for a purely physical bond, or any other bond really. Epoxy rely's almost completely on a mechanical bond so the area must be 100% prepped, that means a thorough sanding and grinding. if it is partially sanded and there are even small areas between the sand scratches even that will decrease bond by whatever percentage is not sanded. I do prefer vinylester (still an epoxy in a styrene matrix) over a straight up epoxy though. A good VE gets ya great physicals at a fraction of the cost and will be more then most will ever need.

Dave, I followed all the rules when I redid my bilge but I do have a question on methodology. Why is it still necessary to sand/grind the existing fiberglass only to adhere new fiberglass to it? I understand if it's covered with gel or paint, the glass needs to be exposed but I mean when it's already bare glass all inductions given still say to grind it. Couldn't you just wipe clean and laminate the new glass?

grinding gives it a good clean tooth

Understood, thank you.