So after 20ish boards glassed with epoxy resin, it seems I’ve developed an alergy to the stuff. I was pretty bummed out about it initially, but I’m trying to be positive and venture into the world of polyester resins. I’ve shaped primarily with polyuerthane so that’s no issue, I’m just hoping some of the older heads here can give me tips on glassing with poly vs epoxy. I got pretty good at epoxy laminations, is poly generally easier? What are they major pitfalls? I know factories like it for the cure time, but can I slow the cure time by using less catalyst? Unforunately, my first go is gonna be a 9’6" for a customer in an 80 degree garage. Typically that would take me ~30 minutes to glass with epoxy but I’m not sure about poly. Poly looks like it’s a bit easier to work into/remove from the glass so maybe I can do it quicker? Thanks for any advice you guys can provide. I know about UV cure but I’ll be using a dark green tint (it’s for a friend) which may inhibit UV curing. I’ve also gotta navigate some cutlaps. I’ve heard stories of chemicals almost burning down garages - what storage precautions are there? I plan on researching all of this but I’m hoping you guys can point me in the right direction.
If you’re a new builder - let this be a warning. Epoxy isn’t the miracle resin it’s advertised as. It’s great in certain respects (mechanically superior to poly IMO) but it DOES have it’s own health implications. Look up epoxiy sensitisation and be wary. I’m lucky in that I only have hives. Some people have resiratory issues or worse. It seems that everyone has their own epoxy exposure limits, so it’s not a matter of if but when, especially if you don’t take the neccesary precautions. This is especially important when sanding “B stage” resin (i.e. it’s mostly cured). Full epoxy cure doesn’t happen until roughly a week after kick. Wear a respirator, eye protection, and long sleeve/gloves when working with it.
For gel time go with UV reactive poly, all time you want, or low reactive one’s as you can find for boat building. Isophtalique resin is mechanically and chemically better than standard orthophtalique.
Use high protection mask. After it’s not so far to use than epoxy. Find more gap at shaping pu versus eps.
80 degree garage and a longboard? Get up at 4am and get the ball rolling so you’ve got it lammed on both sides by 9am. Get resin out of the pail and onto the board as quick as possible. Sitting in the pail shortens your working time quite a bit when its hot out. Get a nice wide squeegie so you can move resin quickly rather than the small yellow ones. Make a good solid waterfall over your rails if you use that method so you don’t waste time fiddling around wetting out the rails. Don’t be stingy with the resin the way you might have been with epoxy. Mix more than you need and as soon as its catylized get rolling. Wet it out, pull it out and get it lapped. At 80 degrees you’ve got about 10 minutes. Get a portable A/C unit.
PS: You can still use UV resin with translucent colored laminations. Use a little less than 1% cat and use the sun to fire it off.
PSS: At 20 boards you don’t have customers you have guinee pigs. LOL!!!
One thing you can do with Poly resin is play with the resin/catalyst ratio. Use less catalyst if you want to slow the curing down. Epoxy won’t allow you do that. UV can be tricky if you don’t have a room that will block all the UV rays, but it is great for a fast curing lamination. Once you have it done, you let the sun hit it and boom it starts curing and it cures fast.
The down side of polyurethane resin is the smell, and using acetone to clean up.
With epoxy, post curing with heat will speed things up. I’ve been lucky so far and have not had a negative reaction to epoxy, my brother is sensitized and can’t mess with it anymore.
UV — For small amounts ( up to 5 gal) buy pre mixed UV 249 Silmar. It can be catalyzed with MEK if desired. All the time in the world. Lay it up and then walk it outside to set. You can easily do a board in one sunny day and curing is not necessary. UV additive settles with time; so keep it stirred or shook. If you use the powder added to Silmar; stir with a drill and metal painter stirrer. I add mine the night before. Stir and then restrir the next day. It helps the powder fully dissolve. Otherwise you wind up with little crystals throughout your lam. If you can do an Epoxy in 30 minutes, you’ll be able to handle Poly UV or regular MEK Silmar no sweat.
I’ve not had any adverse reactions too epoxy, but I do wear a cartridge mask and gloves etc.
Actually working wise, the epoxy saturates much easier in my opinion. I learnt with epoxy, then went to poly for cost on traditional style boards. When I jumped back to epoxy the first time I got the glass to float! As above, you use less epoxy, and if you don’t work the poly in you will see its dry, especially with colour etc.
If your doing cutlaps and are concerned with time you can always fold the cloth on to the deck, wet it out, drop it down then lam as usual. Can’t remember who shared that’s technique but I’ve tried it once and it worked well.
If you can sand epoxy well you’ll love poly. Pinlines prefer to be pulled early than late
Thanks all for the advice - I’ve read it all and I really appreciate it. Looked up solar resin and it looks like the perfect way to go. I’m gonna add a little MEKP Catalyst to account for the resin pigment and hope for the best. Looking forward to the new poly adventure but still a litle bummed my epoxy career has been cut short. Definitely excited to hear poly is an easier sand out as that’s been the trickiest part of epoxy. Hoping I can get some nice glosses going (on the bright side). I’ve booked an appointment with an allergist just to be sure I’m done with epoxy. Thanks again all and feel free to continue chiming in if you have any other advice!