"Is there such a thing as "bad resin"?" Topic

I have some older resin 15mm AFVs I bought about five years ago off of eBay. The manufacturer is out of business, I'm afraid, so I can't go there to ask them about this.

The issue is that two of the vehicles had some kind of oily substance on them, just barely perceptible. I figured it was just release agent, so I washed the models thoroughly as is standard practice for resin models.

Unfortunately, those two models simply will not accept paint, at all. If I try to prime them with Krylon auto primer or Testor's model primer, of if I put a base-coat over the primer, or even if I've put a Future wash over the base coat, it doesn't matter -- the paint on those areas never sets and dries, and it comes off on my hands as soon as I pick the models up.

Nothing I do seems to fix this situation. I've soaked them in Simple Green and scrubbed them, applied primer and base-coat, baked the paint with a heat gun, applied an acrylic wash… doesn't matter. It's like these two models are little Bermuda Triangles of wargaming. Does anyone have any experience with this, and/or have any advice on what I can try next? Is something weeping out from the insides of these things that I'll never be rid of?

Thanks,
jav98

If the mix was a little off, or too much extender (a non-resin used to stretch the volume of resin) was added, you could certainly get an incomplete cure in the resin. I've seen it with a few resin pieces that remain tacky, sometimes for years.

Options include taking a fine grit (like 200) sandpaper to the bare, recalcitrant resin, on the assumption that this is a surface condition.

It's slippery, not tacky? Sounds like the resin wasn't mixed well (possiblty cast at too low a temperature) and they're leaching uncured resin. If they're left exposed to the air it should eventually clear up, but it may take a long while – worst I've seen was over a year, but usually it's just weeks. It can help to leave them on something absorbent (eg a paper towel, changed regularly) and to keep them warm (sunlight works well) but there's not a lot you can do to rush the process IME. You could try hitting them with a hairdryer or heat gun to accelerate the evaporation but beware of softening the model in the process. Cleaning the surface generally won't help – the stuff's coming from inside.

Kind of unusual that the whole surface is oily – the times I've seen it happen it's always been concentrated in one or two spots, or at worst along one side (generally the bottom of an open-face mold).

Could be a mold release residue too.

Some mold releases, especially the older ones can be quite nasty and hard to remove. they aren't really designed for "model work" or production parts that will be painted.

In that case, you might have to go to a really nasty solvent, like MEK, to remove it. Mot really worth it most of the time and pretty toxic.

Battle Works is quite correct in saying that it was a "bad mix job" too. If so, again, you might be out of luck.

(Sorry I don't have a more positive message)

Hello Friend:

You are right, it is bad resin. Don't matter how it was mixed – or should I say how it was mixed by the caster. The problem is with the mixing of the resin it self by the manufactory. A bad mix job by the caster will have isolated spotted areas, a pour resin mix by the maker will have it all over the piece and will leave a cloudy residue in bads and such.

A lot of this resin came out Michigan and several companies had it, it also will eat plastic like an acid. I can't remember how I got past it (it was about 2 years ago). I used baby powder, warm soapy water (heat by the way just makes it worst – tried setting mine in the sun, oven and it sweat like a 2 dollar … well you get the gest), and it just did not work. I think I did used solvent.

I will dig through my old emails and see if I can find the tricks I used to get past it. The resin is secreting oil and what we did was dry the "resin oils" up – let me see what I can find.

Warlord

Calcium bentonite

Have you tried coating it with gesso?

It is a bad mix ,. some cheap resins used #2 fuel oil as an ingerdient . Some doe eventually clen up some never seem to

Try acetone.
Might work, might not.
-Kle.

I notice that you say you've tried "Krylon auto primer or Testor's model primer," have you tried plastic primer? Valspar makes spray cans; I think I got mine at Home Depot. I also think I might have a model from the same out-of-business manufacturer! I haven't used the Valspar primer on it, I'm still trying to get all the old paint off it.

I have had this problem with "old" resins. Two part resin that has been sitting around for a LONG while. It kinda gets 'foamy', and oozes the oily portion out…

Unfortunately, I have no good answer for you. Try sealing it first? Then primering?

old polyester resin leeching chemicals probably…and it is a swine to fix. As it gets hot it will sweat even more and continue to do so for a long time.

Heating it gently for a while, (around 60-70C) essentially baking it, can help, but if it is polyester then the fumes will be noxious so be very wary of this approach…although it helps to sweat out a lot of the fluid quickly.

Most typical sealants will not work due to the nature of the chemicals involved.

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Test the surface for pockets of liquid by using a steel pin to detect cavities, if you find any then drain them of fluid.

Cover it with talcum powder, then wipe off the mess, repeat until you have gotten the surface dry.

Then cover with talcum powder again, ensuring a very fine dusting over the surface. Now spray with super-thin Superglue and it will form an impermeable layer as the superglue bonds with the talc.

Do this a surface at a time so that you have somewhere to hold/stand the model and you don't leave fingerprints all over it!

Any errors, lumps or bumps can be sanded off later.

Its best to do a couple of layers to be certain…but bear in mind that if the models get ehated, such as leaving them in the sun, a warm car and so forth, may cause problems down the line anyway, although generally the talc/CA surface layer is a very reliable sealing layer.

D

antenocitisworkshop.com
governanceoftechnology.com

A lot of this resin came out Michigan and several companies had it,

Its going back sometime now, when polyester resins were predominant, and garage-casters used to bulk it out by using diesel of all things.

This added an even worse smell to the normal polyester as well as often creating liquid pockets in the resin, when those got hot and expanded they would sweat diesel!

In some cases the expansion of the liquid would even crack parts.

It seemed to originate in the states amongst casters and re-caster on larger-scale sci-fi models in particular , although it certainly was't confined to just the USA.

Its occurrence died-out as fewer and fewer people used polyester and swapped to polyurethane as it became cheaper.

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Javelin: Jed suggests going to the Starshipmoddler forums and asking there if the above process fails; as many will have had direct, personal experience with such dubious resin and how to fix it.

D

antenocitisworkshop.com
governanceoftechnology.com

Its occurrence died-out as fewer and fewer people used polyester and swapped to polyurethane as it became cheaper.

Actually this has been with the Urethanes, however I know there has been a lot of experimentations by certain resin makers to keep cost down thus changing the properties of the Urethanes being used on the market.

I can't find the emails but you can try washing with warm soapy water, then I believed I used a "Paint Thinner" from Wal-Mart and scrubbed them down and then I used powder and that helped. The only thing I can think I may have used different was fingernail polish.

Sorry I am so vague but I just can't remember if that was the exact process as I tried many until it worked.

Good luck,

Warlord

Resin supposedly has a very limited shelf-life, of something like 6 months.

It is recommended that you purchase "fresh" resin, but since they don't put dates on the containers, like bread, determining that can be difficult.

It's probably best to purchase from a seller that specializes in the stuff, and has a reasonably high turnover of their product, if you can find one.