UV Epoxy resin, a cheap alternative to 2-component casting

[Spey_Phantom]

i have started preperations for a new modeling experiment, since traditional resin casting is too complex for me, also i lack the finances and space for such as setup, i thought of starting experimenting with this new stuff called UV epoxy resin.

her's an example:
https://www.amazon.com/Resin-Ultraviolet-Decoration-Transparent-Activated/dp/B07FPR3RNQ

usually, resin casting uses 2 components, the resin and a hardner, but with UV resin, you only need one component and can be cast straight from the bottle, drying is with sun- or UV-light. it is normanny used to make custom jewelry, but i think i could use it to make new, or clone, modelparts.

i found a few of these online and could be bought quite cheaply. i found a pack of modeling clay in my stash, which im gonna use to make a mould. note that i have zero experiance in resin casting, so before the experiment goes down, is there anything i should look out for?

[frank2056]

Nils - this looks similar (if not identical) to 3D printing resins, that cure with 405nm light. I'm not sure how well it will work in a deep mold, since the UV light has to reach every bit of resin to cure it. Otherwise, you'll end up with a cured surface and  a gooey mess below it.

The resins are not healthy in liquid form; you'll need to invest in latex (or similar) gloves and some goggles. They also tend to stick to everything and make a sticky mess. Invest in paper towels and plenty of alcohol (for cleanup) Isopropyl works well, but may be very difficult to obtain now. Denatured alcohol (Methylated spirits in the UK, possibly the same in Europe) works great, too.

If you soak the part in alcohol (to remove any uncured resin) you will eventually foul the liquid with uncured resin. Either shine a UV light on it or place it in the Sun to cure and precipitate the resin. The solids can be disposed of as solid waste.

Make sure you have a clean area for playing with the resins. I have a plastic tray under my printer to catch any accidental or catastrophic spills. I can't stress enough how messy and sticky uncured resin can be.

I used a UV nail curing station like this one: https://www.amazon.com/gp/product/B07F1PD25R/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
for a while, and it cured my prints in 2-3 minutes.

I also used this: https://www.amazon.com/gp/product/B072XJ55DG/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
solar powered turntable under the curing station - the UV was more than enough to power it.

The clear UV resins tend to yellow badly when they're fully cured. One way of mitigating this is to add a small amount of blue pigment for UV resins.

If you decide to experiment with other resins, there are water washable resins that work well. If there's a Makerspace or equivalent near you (there are several in Belgium), ask them if they have any resin printers and if so, if they can lend you a few ml of resin to experiment.

[Weaver]

You can get tubs of wipes pre-soaked in Isopropyl alcohol - we use them at work.

[Rick Lowe]

You can get tubs of wipes pre-soaked in Isopropyl alcohol - we use them at work.

And they're sold in packets as cleaning cloths for spectacle lenses.

[kerick]

I'm going to try this asap. Sounds like a great way to solve my Tornado Hindenburg tank problem. I'll wait for a sunny day and just place it outside to cure. I wonder if placing close to a fluorescent light would work? I'm sure it would take longer.
Do you know if this resin is as thin as water or thicker?

[frank2056]

Do you know if this resin is as thin as water or thicker?

Depends on the resin; some are almost water thin, but most are like a cheap syrup. Sticky, messy and in some cases, stinky. The isopropyl wipes may help to get uncured resin off hands, fingers and surfaces but it may leave fine streaks of uncured resin on the model; that's why soaking the model (or cast part) in alcohol is recommended. It will dissolve and remove uncured resin without leaving a trace.

A fluorescent bulb may work, but it's going to be slow. Direct sunlight should work. A 405nm UV flashlight like this will be very quick.

Tamiya makes a light curing putty that is basically a UV resin in putty. I was disappointed by the results; it didn't stick all that well to plastic and flakes off when sanding.

I've used UV resins to fill gaps and it works OK.

[jcf]

i found a pack of modeling clay in my stash, which im gonna use to make a mould

Make sure it's sulphur-free modelling clay and chill it in the refrigerator after you've formed
the mould and before you remove the part, also chill the mould before pouring the resin.

After the resin has cured chill it again before trying to remove the cast part if you want to use
the mould again.

[kerick]

I gave the UV resin a try and here is what I came up with. First of all the bottle I bought at Micheals craft store was $16.99. Not super cheap but not bad either. Also a pound of modeling clay for a mold. I cut a pill bottle in half to hold the modeling clay so it wouldn't deform later.



I made "feet" to hold the pill bottle half from rolling around with Aves epoxie sculpt.



I had to make the mold extend beyond the pill bottle to fit the length of the fuel tank half. Actually making the mold in the modeling clay was easy. I just had to make sure clay was pushed all the way up to the edge of the tank to get a proper complete shape of the mold. Detail was very good except where clay didn't get pushed into the corner where the fin met the tank. If I did this again I would push a little clay into these type of spots before pushing the tank into the clay. As I wasn't going to use the fins anyway it didn't matter here.



I took the mold and the UV resin outside in the full sun and set up on an overturned trash can. All set to go and I thought I should have a mold release agent. I grabbed a can of WD-40 spray oil. One little squirt was more than enough to coat the mold. Probably too much. I tipped the mold up to get as much to run off as possible. I stared to fill the mold with resin and it started to harden almost immediately. It took a couple of passes to fill the mold and just a tad more to make sure it was filled all the way. I had scribbed a line around the top of the tank half for a fill line. I turned the mold about once a minute for five minutes. More than enough time but I wanted to be sure.



After it was hard I removed the part by prying under the end of the tank with a model knife. It was a little stubborn but came out in one piece and didn't destroy the mold. I'm not sure if the WD-40 made much difference. I would have to try a new mold without oil to see for sure. I refilled the mold for a second part and it came out nearly as good as the first. Not bad for modeling clay.



The mold didn't look too good after the second part was removed. I blame it on the WD-40. After lots of sanding these should be usable parts.
Of course, by the nature of the UV resin you can only make one sided parts. If I were going to make more than a couple parts I would use a silicon type mold material that would be more durable. The biggest advantage I see here is the curing time of only a few minutes in direct sun and very clear resin material.

[NARSES2]

Interesting experiment 

[Rick Lowe]

Interesting experiment 

Indeed, and it looks like it might be a way to make replacement broken/cloudy/missing clear parts... hmmm 

[NARSES2]

Interesting experiment 

Indeed, and it looks like it might be a way to make replacement broken/cloudy/missing clear parts... hmmm 

Yup, might produce more consistent results then plunge moulding as well ?

[Spey_Phantom]

looks good, this might work.
i have some broken part that need replacement, im still waiting for my order to come in, when it does, im giving it a go.

[kerick]

I did notice when I filled the mold I was in the sunlight and the uv resin was hardening slightly even as I was pouring it. It would be better to fill the mold inside then move out into the sunlight for a smoother finish on top. Of course if you use an artificial uv light source that wouldn't be a problem. I'm going to try it in some silicone molds I made many years ago.

[Rick Lowe]

Interesting experiment 

Indeed, and it looks like it might be a way to make replacement broken/cloudy/missing clear parts... hmmm 

Yup, might produce more consistent results then plunge moulding as well ?

I would say so.
Re-reading the earlier part of the thread, you'd need to experiment to find a type that won't yellow with age, though you could always make another replacement down the track...

[kerick]

I bought a $3.99 black light bulb so I'll see how that works.