Gelcoat

I bought a small can of white gelcoat from West Marine today, and my understanding was that it doesn't need the wax layer over the top to harden up. This'll sound bad....... but I just can't get it hard!

Do I need the wax? Or am I not adding enough catalyst? I'm just touching up a daggerboard tip and some edges that got bunged up, so I'm just dabbing it on and not spraying. I'm mixing 3 or 4 ounces at a time, and probably putting in ~10 drops or so of the catalyst. The directions on the back says it should go off in 10 minutes, and I'm left with a rubbery product after an hour.

Temp is about 80F, humidity was 60% or so.

I'm scared, confused, pissed off, and armed.

You go Karl! Good luck, I'd always heard covering it in wax paper worked. I dunno thougn.

Wax paper laid over the wet gel always works for me.

Just be sure to lay it on smoothly so there aren't any air bubbles under the paper. leaves voids that require another "dose" of gel.

either that, or grind up one of your Viagra tabs and stir it into the mix !

If the resin is hard but the surface is sticky then you need wax (or more of it) if the it just stays rubbery in the pot you didn't put enough hardener in it...

Here is the quick and dirty assessment, lot of problems are caused by not mixing it well...too many people put the MEKP in the resin and run the stir stick around the container a couple times....you need to thoroughly mix it...also you don't work out of you mixing cup...especially with small batches, as the resin on the sides of the cup rarely get completely mixed...so mix in one cup then pour it into another to actually work from...those two things will save you a lot of headaches.

Did you stir the resin can well before you poured off what you were going to use? If not, the wax will not be mixed throughout the resin and if you do little batches at a time, by the time you are half way thru the can, most of the wax has been used (floats to the top) and your gelcoat surface won't harden . I have found that most Gelcoats that come "with wax" seem to have a marginal amount of wax at best, I make it a practice to put in an additional small amount to insure a good hard sandable surface.

In general it sounds like you went light on the MEKP but its hard to say for sure as they there are other factors to consider...

Regards,
Bob

Karl,
Go watch my gelcoat vid on youtube. Occlude o2 with plastic or PVA or whatever. If that doesn't work, the gel is old, notorious at big box marine because hardly anyone that knows how to use it buys it there. You can spike old gel with a few drops of cobalt, if you have any of that super toxic stuff laying around. Most people don't.

Go up to your local glass guy and have him pour you a quart from his drum. have him mix in a little Duratec Clear.


Hope that helps.

Apply some heat from a hair dryer. Gently.

Good advice up there...but heat won't fix what appears to me an air inhibited cure. Once that has happened, there is no going back unless it involves chemicals to strip it off.

I have had failure of the wax eat my lunch and steal my girlfriend before (or failure to correctly follow some of the advice listed above). I much prefer to top coat the repair with PVA or use Duratech additive - i feel they are much more reliable options to the wax.

Thanks guys, and Pete. I wouldn't be surprised if the stuff was old. Boating in Minnesota is extremely popular, virtually everyone has a boat of some variation, but most are aluminum fishing boats, and I don't know anyone up here who does their own repairs on glass. There just is many places to source supplies, being new to this a bit unnerving as well. Wood is so simple in comparison.

I thought I was mixing well enough, both when it was in the can prior to adding the catalyst, and after it was added. I'll try pouring it off in a seperate container once mixed, and then covering it with some plastic after its applied.

DO NOT Use Plastic
If you do, you will be even more unhappy than you already are.
Wax paper is the only way to go.

Is parchment paper the same thing as wax paper?
I'm thinking not.

Wax paper is Wax paper Karl.

You get it at the grocery store next to the tin foil.

...next to the parchment. Parchment is used in baking; in the oven.

Right, I know where my hats come from. I was just fishing around in the pantry, (I wrote panty the 1st time, which'd be odd if I came across parchment), anyway, and I found parchment paper. It worked, nothing stuck to it. Blue 3M masking tape refused to sick so I figured it'd work.

The stuff I put down last night was rock hard this morning, so I roughed out the sanding and figured out where I needed to build it up more yet and laid down a second coat. I put in way more hardener than I thought I needed, and I probably did go too much because it started to thicken in a few minutes. It was also 90F today, but that set hard in 1/2hr, which was helped a bit by the sun.

They aren't perfect, but both have tips again. I need to do some more touch ups yet, but I'm leaving for Nebraska tomorrow morning, so thats not going to happen.

Thanks again for the help guys!

rate of reaction = heat of reaction

If its still rock hard after 4 hours call a doctor.

Grab some of your girl's hair spray. Spray it on there. Then apply just a little heat from a hair dryer. Don't go melting anything. That will start the reaction. Wait 24 hours then sand.

Mike, do you find this works better than PVA? A lot cheaper...probably easier to cover with as well. No drip.

No better or worse really. I like it better because it comes in an airasol(sp?) spray can. So I can just keep it in my kit and it's ready to go. You can mist it lightly and it gets a decent finish.

I think your ratio's are off. When using layup resin one ounce of resin would use 10 drops of hardner. I would assume that gelcoat would be a similar property. Pledge in the spray can is a great air inhibitor and readily available.

Grab some of your girl's hair spray. Spray it on there. Then apply just a little heat from a hair dryer. Don't go melting anything. That will start the reaction. Wait 24 hours then sand.

Do you still have to go to the doctor?

They do say cold causes shrinkage

I agree. The number that comes to mind is 12 drops of hardener per ounce for polyester resin. I've had good results using the west marine finish gelcoat with wax in the formula. Mixing throughly is also important. Once you think you've mixed it enough, mix it some more.

sm

http://www.youtube.com/watch?v=en-8SbhdF_k&feature=related

pretty good video on gel coat repair.
BTW it states 20 drops per Oz

What brand of hair spray?

1 oz of fluid is about 500 drops. If you are looking for a mixture:
1% = 5 drops
2% = 10 drops
4% = 20 drops
I use about a 2% mix for regular resin. I use about twice that much for gelcoat. Gelcoat takes longer to dry. Gelcoat is, in effect, resin, pigment (for color), and a thixotropic material. The additives retard the gelling properties of the resin.

If you really want to know and are interested do this experiment. I took some resin classes in college and one of the requirements was to see what resins, gelcoats and epoxies did with different hardener ratios. I took an icecube tray, put equal amount of the same product (ie resin) in each of twelve compartments, then catalyzed them with different amounts. Start with lower than recommended, say 1/2% and increase by 1/2% each until you get to about 6%. Do not stand too close, that 6% will smoke. See how long it takes for each to harden. Your hot one will harden in minutes and probably crack. The slow one may not harden for a couple of days. You will get a really good idea about how your resin reacts and know what you will be comfortable for you.

Dr. DeLave!!!

EXACTLY!!!

Is there a theory on slow vs quick hardening and strength?

I'm not aware of any. However, I've heard that using too much catalyst with epoxy can leave soft spots. Can't speak to the truth of it.

I can also tell you, from personal experience, that you certainly can add too much catalyst.

On one occasion I was very impatient, it was quite cold and I added lots more than called for.

The mixtures heated dramatically, then bubbled into froth and finally harden into a gooey consistency like messy foam.

It was very interesting to watch.

The final mess was (shall we say) less than useful so don't get carried away, as I did.

This looks like Dan! -kinda

The gelcoat hardening must have been related to the paper being in the panty er pantry..

Most likely the problem was not enough hardener. The other things were just a bit helpful. If you stir it well I am not sure it helps to dirty two containers. I personally only do small batches at a time so I do not waste it when it hardens quickly. I also use rubber gloves because the stuff is a pain to get off. You can also put "liquid gloves" on which keep the stuff from sticking to your skin.

What is the problem with using plastic? I use it regularly with gelcoat and polyester. Never had a problem. In fact I think I remember someone telling me that if you put plastic or waxpaper over it as it hardens then the wax stays in the polyester so the next coat will stick better.

I put cloth or chopped cloth on with polyester initially and then put plastic on, then I squeeze out as much resin as I can and then put a many times folded rag on top of that and then a piece of wood to hold it in place and then I put as many spring clamps to push on it as I can fit. This is to squeeze out more resin. My repairs come out excellent. Took me many a repair to figure this stuff out.

Anyone know where I can find carbon fiber in cloth or ribbon at a reasonable price?

Nice goggles, are those Barz?