How long is long enough?

How long do you guys, that mold fish in bondo, normally wait before de-molding your fish? On my first couple of casts, I did them late at night and didn't "get around" to taking them out until the next and everything turned out okay.

Apparently, I'm getting into too big of a hurry, lately, and have screwed up a couple of my last attempts. Yesterday, I waited 4 hours before trying to "pull" a fish. It was still soft around the wooden block area and messed up the back side of the replica, in that area only. Since I intend on really only finishing one side of the partular fish, instead of pedestaL mounting it, it will still be usuable. BTW, the mold was completely cool, and I was under the incorrect assumption that it then okay to de-mold it. :-[

Why would only one spot be still soft after all that time? And, I know I mixed it up real good. Nowhere else was there a problem, either. ???

 

Well, it's happened to me twice on the same mold. :-[ I've yet to get a good cast from this particular rainbow mold... I'm pretty sure that I didn't get the catalyst stirred well in one of the 4 cups that I used the last attempt. On this attempt, I mixed the heck out of the resin. And, why would that occur only in one spot when the resin was distributed throughout the mold? ??? And, both times, it happened in the same spot, on the mold. I just can't make sense of it.

You know what, I set it outside on the ground in the sun to cure. A cold front had come through the day before and it was sitting on the cement. I guess the cement could've been too cold. The air temp was probably 70, but I figured the sun was warming it up. I tested it to see when it heated up and then cooled. I let it set for a couple hours after this occcured, too.

I'm about 99% sure that it was an untreated piece of pine from a 2x4, but with all the duck hunting I do, i guess I could have grabbed a piece of treated stuff, by accident, but I doubt it. In fact, I remember purposely not grabbing the treated stuff because I was worried that it would be too hard. While using some of my treated stuff, I couldn't even get a nail to start without bending it, the other day while working on one of my pit blinds.

This is driving me crazy. I've done tons of work on boats using fiberglass/bondo/gel-coat and never had a problem with the stuff setting up, either. Then, I mix it up as usual, spread it into a closed mold and bamm, things start going hay-wire...

For now, I'm leaning toward the temp difference between the air and the cement as being the cause, but I definitely ain't certain, at this point. And, the uncertainty sucks.

 

Let me add, it happened on the same side, in the same spot of the mold, twice. Both times the cast was perfect on the "show-side", too. This is really weird. Maybe it is the wood. I wish I could remember which side I bonded the wood to before I closed it up.

 

The resin is stored in my shop. I haven't had any issues when I've used it for other stuff, just when it's in the mold. In fact, I made some rocks and other stuff with the same resin and it performed normally. I'm really confused here.

But, one thing I'd like to add is that whatever is happening is affecting the already cured gelcoat, as well. It's becoming soft and is actually tearing open when i try to remove the fish.

I'll definitely take a pic, later.

 

Here's some pics of the first one.





And both sides of the second.







I used the same resin on the fin sections of the mold with no problems.

The fish had some seriously funky fins and I tried to extended with fiberglass to make them look less worn. I'm not done shaping them, yet. The dorsal wasn't great and the tail was really bad on the actual fish.

 

So, no one has a clue what could be the culprit, here? :-[

It really is confusing to me. Like I said earlier, I've dealt with fiberglass for many years while working on boats. I've never seen it do anything like this, and now, it's happened twice..... The gelcoat getting soft is really baffling, to me.

 

Here's another question.

If this had happened to you, what would you do to eliminate all possibilities that it could happen again on your next attempt?

 

I "think" it's probably the thickest, since it's where I'm attaching the block of wood. I even applied more fiberglass, to that area, when I attached it.

Also, the gelcoat isn't just cracking, it's getting soft, as well. What could do this? You'd think that it'd have to have gotten very hot to "melt" the already hardened gelcoat, wouldn't you? uggggh! I'm about ready to give........:-[

 

Should I put down a thin layer of (resin/fiberglass chop) throughout the mold halves and let it completely set, before adding the block? This would give it time to cure, before adding the block and then fiberglassing the two halves together... do I have this right?

Thanks for help, Again-Mike