Resin casting problem

[JimVarnellABH2USN]

I have recently started casting things in resin, everything has been going smoothly until the last batch of castings, I mixed the resin properly and everything seemed to have blended well, curing went off as expected and de-molding was fine, I checked on them today and it seems something went wrong, there is a sticky coating of the part B in some areas and a kind of spider webbing look going on in some of the surfaces.

Now, my question is, is there a way to clean this up or are they trashed? I was wondering if the room temperature had anything to do with the curing process as the temp seemed to drop in the room rather steady. If there is a way to salvage them I'm all ears? If not I'll trash them and cast new ones as soon as I get more resin, which I have a lot of castings to do still.

Any suggestions would be great......

[OS1880]

I've had that problem on a few occasions. I think it was caused by the resins not mixed correctly ... too much of B or not enough of A. I let it cure for a few days sometimes it worked sometimes not. But each time the area in question was left with a void under the area in question and a lump. If it was area with deck detail I started over. If it was an area that would be covered by a structure I sanded the area then filled the void and continued on.

[dafi]

I had similar results and my suspicion was not the ratio of the two parts, but not having stirred properly the two components before using. Especially the resin part has some issues of separating thin and thick stuff.

Cheers, Daniel

[JimVarnellABH2USN]

Thanks Daniel that is what I figured happened, so I'll trash this set and cast a few batch. Lesson learned.

[Chris Decker]

Mixing resin can be a finicky mistress. Couple of other things to watch out for:

1. Is where you store the resin heated? If the resin got too cold, it could have gone bad. Had this problem a few times in my day.

2. Order if mixing is strangely important. When using smooth-on for example, you can Mix A into B and be fine, but if you go B into A, it will often give you the results you see. (I might have that backwards, it's been a few years).

3. We called this weeping, and it's toast, You can clean it up perfect with acetone, and then a few days later it'll be back. If it ever does stop, then you get a white crusting. In short, not worth it, throw them out.

Cheers
Chris

[ModelMonkey]

Mixing resin can be a finicky mistress. Couple of other things to watch out for:

1. Is where you store the resin heated? If the resin got too cold, it could have gone bad. Had this problem a few times in my day.

2. Order if mixing is strangely important. When using smooth-on for example, you can Mix A into B and be fine, but if you go B into A, it will often give you the results you see. (I might have that backwards, it's been a few years).

3. We called this weeping, and it's toast, You can clean it up perfect with acetone, and then a few days later it'll be back. If it ever does stop, then you get a white crusting. In short, not worth it, throw them out.

Cheers
Chris

I have been sorely struggling with this very issue and your explanation about which part to pour into which part makes a lot of sense. I can't begin to describe how many botched 1/125 scale 5-inch single mounts have gone into the trash, including a couple of casts that ruined the molds.

The issue was bad enough that I shelved the idea of casting a 1/350 Saratoga CV-3 hull I'd scratched in resin. Looks like I may be able to give it a go.

Thanks for your insight!

[JimVarnellABH2USN]

Mixing resin can be a finicky mistress. Couple of other things to watch out for:

1. Is where you store the resin heated? If the resin got too cold, it could have gone bad. Had this problem a few times in my day.

2. Order if mixing is strangely important. When using smooth-on for example, you can Mix A into B and be fine, but if you go B into A, it will often give you the results you see. (I might have that backwards, it's been a few years).

3. We called this weeping, and it's toast, You can clean it up perfect with acetone, and then a few days later it'll be back. If it ever does stop, then you get a white crusting. In short, not worth it, throw them out.

Cheers
Chris

Hey Chris,
Thanks for the tips, I did realize that I had mixed B into A and there it was the "weeping" effect, thanks for your insight into this problem, being new to resin casting, it was a good learning experience and not one I will be repeating. Since I posted this question about the issue, I've learned a lot of tips for resin casting and not saying I'm an expert, far from it, but I have improved greatly to the point I'm not afraid to try casting of anything, it I screw it up, I make notes on what went wrong and correct the problem moving forward. I've recently completed casting an entire class of 1/700 scale Sturgeon Class of submarines and had some issues but nothing to dramatic to trash them, my biggest problem is over pouring, but at least its not weeping. Again thanks for your insight into this issue.