little problem with epoxy, need help

General Discussion
1

Hi everyone

I started laminating a woodenboard using RR epoxy. I did mix the proper amounts of resin, hardener and additive F.

I laminated the first 5.5 oz layer, everything went OK except that the resin is quite thick, since I only got fast hardener (F) I didn’t feel like heating up the resin. Everything was cristal clear after the cure.

I read that epoxy could be mixed with ethyl alcohol in order to be less thick. Is this true?!!

After a couple of hours I sanded the first layer (bottom) in order to laminate the deck, I sanded with 80 grit and some parts with 120 grit, I used the vacuum to clean the board and then rubbed the areas with ethyl alcohol in order to prevent from having grease around.

After the alcohol evaporated the surface kind of remained whitish, milky (area sanded with 120 grit)

I laminated onto that and I thought with the resin the milky aspect would disappear but it didn’t, it remains kind of whitish, other areas that were sanded are cristal clear after lamination.

I don’t understand what happened.

Is it because I sanded with 120 grit?

Thank you for considering my request.

2

hmmm… seems odd. – 120 grit shouldn’t have caused that… i often sand down to 60 before doing a final gloss coat

I’m not a scientist and don’t know the difference between ethyl alcohol and denatured, but I’ve always used DNA with no problems. in fact, most of the time I don’t use it at all, i have one brush that i just keep to brush off the excess sanding dust and go to town with the next coat…

3

tnx for the infos!!!

Well I will try differently for the next layers and I might see what caused all this.

All I know, the spots nose and tail turned out whitish, those are the areas I fine sanded with 120 grit.

Next layer no 120 grit and no ethyl alcohol, well I think ethyl alcohol is the same than DNA, denaturated means they put stuff so people would not use it to produce alcohol and drink it!!!

Before people would go to the drugstore, buy alcohol, drop berries in it :slight_smile: wait a couple of weeks and they produced something nice to drink but now no way to get alcohol at the drugstore that is not denaturated.

4

The areas sanded with the finer grit may have left fine scratches that hold dust, regardless of the DNA wipe. This will leave a haze. Stick to 80 grit and use plenty of DNA with the wipe. And do wipe… if you just wet it, and let it evaporate, the dust is left behind. You should flood the thing with DNA and really give it a good wipe… or two.

5

I am guessing you did not wait long enough for the resin to cure, so when you wiped it with alcohol it penetrated and partially broke down the surface of the epoxy shell (since alcohol is a solvent of un-cured epoxy).

Additionally, is your ethyl alcohol 200 proof? Anything less than 200 proof is partially water, which again is no good for uncured epoxy.

6

Yo O.P.

Wear rubber gloves all the time when you’re handling the board during lamination and fill coat work. Sanding to make the surface you’re applying the fill coat too as true as possible streamlines the final sanding process. If you have some surfaces that aren’t true after laminating do a little basting particularly along the lap lines. 80 Grit would be my choice for fairing the lamination. Be sure to blow the board off thoroughly by blasting it with air under high pressure. Water in the smallest quantity is your enemy. There is no reason to use alcohol if you don’t touch the board with you hands, tuck it under your bare arm or rest it on your head during portage. I drop by the finest domestic epoxy only surfboard factory on a regular basis and alcohol is seldom if ever used there. I see no reason to use additive “F” for the lamination process, however it does make the fill coat level nicely and prevent fish eyes.

I hope something I offer is of worth.

No Worries, Rich

7

thank you so much for all the infos!!!

To answer some questions :

I used additive F in the lamination process because I thought and read it may be used when conditions regarding temp and humidity are not the best…that the resin soaks into the fabric way better.

When I laminated I didn’t have 80 degrees in my garage but more than 60 of course!!! The resin was thick so I used additive F so it would be less thick.

My issue as well was the resin being too thick, just a hassle to wet out the fiberglass.

I read on the internet that people either heat up the resin or add some ethyl alcohol!!!

Well I didn’t do any of these because using F hardener meant a shorter pot life when heating the resin and mixing ethyl alcohol was not the way to go since I didn’t know what may happen.

I didn’t use high pressure air because I read as well that sometimes little oil drops may come out or I didn’t feel like having dust all around.

Regarding sanding, I also read people wash the boards before sanding!!! Right or wrong?!!

Regarding my adventure :

I did another lamination and the same thing happened, the cause is the sanding.

As mentionned I used the F hardener (Fast) so according to RR tables set time is 2.5 hours, I waited 20 hours before sanding for the other test.

Was I supposed to wait longer?

I then sanded with 50 grit some areas that kind of were uneven, well I sanded and when you sand it remains whitish wich is normal when you sand. I cleaned again with ethyl alcohol, I know I know but I just wanted to make sure why it turned out that way.

I then laminated and those spots where I sanded quite a lot turned out with a ‘blush’.

I sanded once again but this time didn’t use ethyl alcohol, just wiped it properly, then with a brush.

I just put some resin on those areas, the same thing happened, where I sanded a lot those areas remained whitish afterwards!!!

The weird thing : the areas where I sand a lot have those problems, I sanded other spots but lightly and I didn’t have that problem.

I must admit that I didn’t put the board in an oven to cure, just left it on its stand and let it cure with room temperature.

Well I am a rookie with that epoxy stuff :slight_smile:

Question : when do you know the epoxy is fully cured?!! I waited 20 hours and with what happened it wasn’t cured so just to avoid the little mess what can I do to know it is cured? Just check the sanding paper to see if it cloags up right away?

Thanks again for helping me out

8

Did you sand with bare hands or with gloves on?

Board and resin should be at a minimum of 65 degree.

Additive “F” isn’t going to compensate adequately for low temperature IMHO.

My rule for laminating and fill coat is get the work and resin to well above 70 degree (I just put both out in the afternoon sun) Then I move into a open shaded area so the work will be cooling while I work. I’ve had excellent success with this method.

Post curing at a slightly elevated temperature is always the call to get a complete cure. Around 125 degrees is a good call. There are lots of pros glassers that post here. Hopefully one of them will chime in with some good advice.

No Worries, Rich

9

May want to check, but I’m pretty sure Addative F is not a hardener, but helps with finish, and you don’t need to sand/alch. wipe between coats. At the temps you mention, I’d guess you may have benefited from waiting longer before sanding.

10

I handle the board wearing gloves so I won’t leave any grease on it.

I guess the cure was not complete therefore when sanding too much it smeared and by laminating onto it I got that haze.

I thought that after 20 hours it would be OK but it was not the case, I did some sanding recently and the epoxy was way harder, I put some resin on those sanded areas and no haze appeared so I came to the conclusion that the board was not fully cured when I sanded.

Next time I will be more efficient, thanks again everyone for dropping by and leaving great technical comments.

11

Sounds like you need to bring the temperature up. The colder it gets the thicker your resin will get. 25 degrees celsius is ideal for epoxy on the first cure.

12

I wish everyone would put the damn solvents away for good. They do nothing but f#%k up this system. They are TOTALLY unnessasary in building boards. Some other applications maybe, but surfboards NO!! The alcohol attacked the surface of the resin while it was still uncured. You then laminated over the solvents and trapped them inside. The thickness of epoxy doesn’t mean it won’t wet. Epoxies have better surface energy that polyesters and will wet more effectively at higher viscosities.

13

BTW, we made a video … it has the correct methods from over 25 years of production. surfingvideos.com

14

Thank you very much for all the infos.

I am a rookie with epoxy and I made a mistake regarding the cure and the ethyl alcohol.

Next time when I laminate I know for sure what to do and not to do.