I am looking to coat some insects in something very hard and clear. I have tried an acrylic resin I got at hobby lobby but it doesnt cure hard enough… I dont want to be able to indent it with my fingernail. Anyone know what might be best?
Get the Polyester resin - it’s very hard.
cool, I will look into it. Thanks.
Bahh… turns out thats what I was using… not sure whats going wrong.
Make sure you have the hardener proportions correct - it makes a big difference.
Yeah, I have a dragonfly encased in polyester resin for around 20 years. The plastic has darkened a little over time, so has the dragonfly. But the plastic is still solid and hard. The proportions of resin and hardener have to be precise, and you have to mix it well.
the problem with that theory is this… The left over resin in the bottom of the cup cures PERFECTLY hard… exactly the way i want. The thin parts I’m painting and dipping on are soft and sticky and don’t cure properly. I’m thinking it has to do with the chemical reaction in a larger amount as opposed to a think veneer that I am trying to use… but I don’t know.
If I were encasing the insects in a block of resin it would be perfect… but I’m not… I’m trying to just get a hard, clear, sturdy shell over them 2 or 3 millimeters thick.
Oh…
You are going to need to use epoxy. I think that is the only commonly available clear plastic that has any hope of being as strong as you need. Try some samples with a mixing nozzle (to avoid air bubbles), and see if it works for you.
You might give a call to a museum’s insect department or a college and ask if they have any ideas. They might be doing this kind of thing of displays.
Al the Google returns are casting blocks rather than just a coating.
BTW, a zillion years ago, in my first job out of college, I talked to a company that made UV curing equipment. They gave me some samples of ‘butterfly’ refrigerator magnets (they were actually paper) that had been coated with a UV-curable plastic and then cured by light. I still have some. They were pretty strong and durable. So, what you want is possible, but it may not be easy to do in your house.
Wow - they are still in business! You might want to contact them.
Ok, that’s not what the casting resins are intended to do. So as mentioned above, epoxy may work. There are clear epoxy mixes made for coating table tops that may do what you need.
Fantastic guys, thanks!
For a cheap experiment, you could try using a clear nail polish. Look for something like “top coat” on the label.
I actually work in the resin (unsaturated polyester and vinyl ester) industry - your last post sounded like you had solved the problem, but if you haven’t:
Temperature. TEMPERATURE!
The reason it cures nice and hard in your cup is that you have a nice little mass that, as it cures, builds enough temperature to drive the curing reaction to near completion. A thin layer doesn’t have the reactive mass to do this.
If you’re still having trouble, coat the part (or insect, or whatever) then put it in an oven. I’d try to avoid your kitchen oven, just so it doesn’t smell like a chemical lab. I’d say an hour or two. Try 150 F first, and if that doesn’t work go up in 25 F increments. If you have to go so far that the resin starts to discolor, well, then you need to try a different resin system.
Smooth-On might have what you need, specifically this category. I’ve never used the laminating stuff before, but their casting products are excellent and they’re very good at advice.
For God’s sake, let them LIVE! 
That’s exactly what I was thinking! I plan on trying this… and if that doesnt work trying clear epoxy.
If that doesn’t work, how about “hard gel” nail coatings? I think they’re UV cured, and extremely durable - they can last more than 2 months on nails.
My first thought when you mentioned a thin coat was spray polyurethane. Folks who know better than me: is there a reason that wouldn’t work?