Mekp vs UV cat post curing time

General Discussion
1

…guys,

whats your opinion about that?

-for ex.: at 25ºC x 24 hours x 7 days is the “normal” post curing time with Mekp

some say that with UV cat there s no need for post curing after sanding

from mid 80 s to now, I tried several ways and I see pretty different results

ways like: lam with 1 X 4 oz per side and gloss in the deck and speed finish bottom and all type of combos; E glass, W glass, S glass; same plugs (and same thickness and type of shapes) and same fiberglass combos; Reichhold, Silmar, Cray Valley, Elequeiroz, etc resins, some epoxies in late 80 s

glassing with bad weather and with perfect room conditions; bad weather and bad room conditions and bad winters post curing conditions; bad weather but then curing in perfect environment;

and a long etc

basically I just see that if you let the board in a good room for months, no matter if it has 1 4oz on deck, the board will be much stronger (in a realistic way) than a no curing ( with UV cat) and a week at 25ºC with Mekp boards

2 
Howzit reverb, I used UV for a few years and the lnger you leave it in the sun the mre it cures. After about 15 minutes it should be cured enough to flip and prep for glassing the deck, I have done a whole board in 1 day. Aloha,Kokua
3

.

4

…Kokua not in the work process

I mean, Im talking about after the finished product

-Screwfoot

very interesting that observation

thanks

5

UV requires no post-cure. All the little polymers for nice long chains very quickly

and there’s not any more ‘‘curing’’ to be done. MEKP initiated reactions, especially

at normal surf industry catalyzation rates, form shorter chains that can add a polymer

or two over the following couple of weeks.

Letting your lam air-cure (don’t hot coat ASAP) will also add a little strength to an

MEKP lam. And lighten it, because more styrene can fume off. You might be hard-

pressed to measure the weight savings, though.

6

…well, this UV no more post cure stuff (like I said in the previous comment) I have been hearing from several years seems pretty right

I understand the fact that there s no “destruction” of the chains like with Mekp, etc

so is less aggressive and the reaction is completed

but the question was intended in a comparison with Mekp systems in several situations (materials and weather, etc) like all the “experimentation” that I mentioned in the first comment

I mean, there are real differences letting the board cure (with MEKP) 1 week in really bad weather or 5 months in a perfect room conditions

so, you mean that there s no any advantage or difference in let the board post cure (with UV cat) for a long time or not

and no matter if the weather is super cold (5 - 10 ºC) and with high humidity for weeks, the board is just ok when finished…

7
Quote:

so, you mean that there s no any advantage or difference in let the board post cure (with UV cat) for a long time or not

and no matter if the weather is super cold (5 - 10 ºC) and with high humidity for weeks, the board is just ok when finished…

A resin chemist could give you a more complete answer, but here goes…

All resins have working condition parameters, if you’re outside of them, it will affect the reaction

and likely decrease ‘‘strength’’ of the yield.

When doing UV lams with proper resin temps and good ambient temps in the light box, once the

timer goes off the reaction is DONE. I don’t think it matters what temp or humidity does after that.

It’s a fully reacted polymer.

8

Is it safe to assume that UV resin goes off more consistantly, under a wide range of conditions, then mekp , therefore resulting in a better board?

I may be a bit off subject.

Thanks, Dave

9

I’m no propellor head when it comes to chemicals, but we use both Mekp and UV, at once!.

Just a few drops of mekp, once that start to gel we stick the board in the light box and blast it with UV for about 10-15 mins when it comes out it is crispy - what I mean is unlike Mekp on its own which would be gum the sand paper a little this doesn’t gum up, which makes me think its cured more than enough in the time it’s had. Also this stops any of the laps falling down then setting in the light box.

We don’t use UV for the hotcoat only the lam.

10

Had another thought, once the board is glossed we leave it for 2 weeks at a good room temp before its polished, sometimes longer if we are feeling lazy.