If you're using the MAS non-blushing stuff that came with the kit, you shoud be absolutely fine with a at least a handful of days between epoxy coats.  I'd worry more about any possible surface contamination, and thus always giving a quick alcohol wipe (giving it more than a few minutes to dry out before applying epoxy) is, I think, a good idea between coats. And if you're really worried, it takes only minutes with a scotchbrite pad to scuff the epoxy before the acohol wipe.  My opinion is no need to sand.

Thanks, I will do that because of dust I always wipe down but will add some alcohol to the wipe down.

Larry  

I'm with Bubblehead on this as far as prep before next coat with MAS epoxy. No doubt in my mind he's got way more experience with this stuff than I can claim!

Working on my Waterlust project has me wondering just how long one can wait before adding another coat if one doesn't bother whatsoever with any kind of surface prep?

I can see all kinds of practical and/or aesthetic reasons for scraping / sanding to make a cured coat more uniform, or blend in edges of fiberglass cloth but if it's not necessary to sand a coat that's cured solid after four or five days I'd rather save my limited patience for sanding for where the efforts are more apparent. or use Scotchbrite.

Scotchbrite is great stuff for breaking a glossy surface down and with so much less labor than sanding it'd be my more frequent choice after seeing his recommendation.

Where I've dripped fresh epoxy onto previously coated but not yet sanded surfaces (it happens, it's no big deal) I find it's not any easier to remove the drips than it is to scrape off drips or runs on uncoated surfaces. Even on a cured but unsanded surface the new stuff seems solidly bonded once it's cured. 

   Yes it seems wherever epoxy drips it sticks with a vengence. I will be adding the rest of the 2nd coat today, as my order of MAS epoxy did not arive till late last night. I really like this forum for all of the help and advice when new builders have a question or problem. Thanks to everyone. Will be posting more I am sure.

Larry

spclark wrote"Working on my Waterlust project has me wondering just how long one can wait before adding another coat if one doesn't bother whatsoever with any kind of surface prep?"

Simple, ask the epoxy manufacturer. They all have instructions on their websites that address that very question. For example, System Three Silvertip (my favorite) can go for 3 days before you need to sand the previous coat. Checking the MAS website will tell you what their product needs.

A generic rule of thumb is that as long as the previous coat hasn't completely cured, you can apply a new one. You can test for this by pressing your thumbnail into the epoxy. If it doesn't dent, you need to sand. Another test is to sand a little bit. If the epoxy doesn't form a fine dry dust, it's not cured and you don't need to sand.

But the best thing to do is to check the manufacturer's instructions.

Laszlo