What are some inexpensive alternatives to epoxy resin for diorama water effects?

Question

I make dioramas and use epoxy resin for water features. However, epoxy is expensive ($80 for a gallon where I live), toxic, and it gets cold where I live, which isn't good for curing. So what are some cheaper alternatives; something preferably non-toxic, relatively cheap, and doesn't care about how cold the garage I work in gets?

Key properties: long-lasting, pourable and hardening, or at least gets somewhat hard. The biggest concern for me is price and temperature. All other factors are more of a bonus. If it's resin-like but cheaper but even more toxic then I'm fine with that.

How long do you need it to last ("forever" vs. max of say a few weeks)? — fixer1234, Feb 23 '23 at 16:23
Do you need to be able to pour it? Does it need to harden? You basically want something that is resin, but doesn't have those unwanted properties? Because if that's what you're after, I'm afraid you're going to be disappointed. Could you tell us what properties of epoxy resin you don't require? — Joachim, Feb 23 '23 at 16:43
@Joachim pourable and hardening, or at least gets somewhat hard, the biggest concern for me is price and temperature, all other factors are more of a bonus. If it's resin-like but cheaper but even more toxic then I'm fine with that. — redfrogcrab, Feb 23 '23 at 16:45
A couple of thoughts on your constraints. 1. Temperature is only an issue during curing. You could use a space heater for that time to minimize the problem. 2. Epoxy being toxic is mainly a problem with the raw resin. Once it cures, it's pretty safe. You can even use resin designed for table tops that's food safe for incidental contact. Occasional casting (e.g., not everyday exposure), with basic precautions for handling and breathing is pretty safe. If you're worried about handling of the cured resin by young children or licking by pets, it's pretty safe at that point. (cont'd) — fixer1234, Feb 24 '23 at 03:34

fixer1234 · Answer 1 · 2023-02-23T18:26:01.473

Something inexpensive that comes to mind is "fake glass" made from sugar. This is what is often used for prop windows and bottles. You can color it or put a clear layer over a painted surface (that can take some heat). Here's instructions for doing it with just sugar, and instructions for a more complicated mix used to cast fake bottles.

The finished items should last a long time, but I don't know if they might attract pests or if they are hygroscopic and could get sticky in high humidity. You might be able to coat the surface with some kind of clear top coat to avoid those potential problems (never tried it).

If the surface to which you want to apply the "resin" can't take the heat, pre-cast the fake glass. I'm not sure whether it's too brittle to try to cut it to shape after it's cool.
There is clear wax sold for candle making, like https://www.amazon.com/Density-Penreco-Candle-Making-Supplies/dp/B0185Y9DOQ/. I've never used it, but it looks like it should work. It isn't cheap, though.

If you don't need too thick of a layer, you might be able to use clear hot melt glue, especially if the area you're filling can take some heat. It is pretty transparent (not like Lucite, but clear and colorless). You can melt a bunch of it in a small pot or craft melter and pour it, or preheat the surface, pump in a bunch with a glue gun, and keep it all hot during the process with a low temperature heat gun. If you get the glue a little hotter than what comes out of the glue gun, it becomes much less viscous and will flow.

Hot melt glue does shrink a bit as it cools. Best case, you will have a divot when it cools that you can top off. Worst case, if what you put the glue in isn't solid, that can distort.
If all you will see is the surface, there isn't really a need to cast something thick. You just need a surface that looks like water. People often do that with Mod Podge, glue, paint, and other materials (like toilet paper to add bulk and retain shape). Aluminum foil is sometimes used as a base layer to get the light reflection effect. How to Make Water for a Diorama - With and Without Resin might be a good start (ignore the resin part). The author uses a specific paint designed for water effects, but people often use regular acrylic paint. There are lots of online resources for achieving a realistic water look.

How to Make Realistic Water in a Diorama | Detailed Guide (2023) goes into a little detail on creating surface texture. The author prefers glazing medium/gloss gel. They recommend a product called "E-Z Water", which appears to be a form of low-temperature meltable plastic. That will probably be more expensive than epoxy.

Sugar is hygroscopic (e.g. the windows on my gingerbread house which were essentially coloured sugar), but it's not insurmountable as you can coat it. There are suggestions at that link, including robust ideas that didn't work more me as they're inedible — Chris H, Feb 24 '23 at 09:50
@ChrisH, impressive construction on that gingerbread house. :-) — fixer1234, Feb 24 '23 at 15:25
not bad considering my 9-year-old did much of it. Apparently this year we're making our own house in gingerbread, and it's rather complicated! — Chris H, Feb 24 '23 at 15:50

score 2 · Answer 2 · answered Feb 23 '23 at 17:07

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Depending on how deep you want the water to be (or rather, how much of it you need to look transparent), you can try using PVA glue.
It cures slowly (requiring cover while drying in order not to get all dusty and dirty), shrinks while drying (which may cause warping of whatever it is applied to), but it is significantly cheaper, can also be dyed, and manipulated somewhat into shapes.

answered Feb 23 '23 at 17:07

Joachim

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PVA glue is mostly water and shrinks to a tiny percentage of its volume, so it isn't good for normal casting. I actually used it to cast something 1 mm thick (https://diy.stackexchange.com/a/265303/28390), and it took something like six or seven layers, overfilling the mold each time. It took over a week with drying each layer. And anything thicker than a film becomes translucent. – fixer1234 Feb 23 '23 at 18:10
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@fixer1234 Yeah, it certainly is not optimal, but I've seen some pretty good-looking results in the diorama scene. And the OP's goals are not very clear. – Joachim Feb 23 '23 at 21:26

score 2 · Answer 3 · answered Feb 23 '23 at 19:00

Woodland Scenics web site carries a few different water related products. There's no indication of temperature problems as the product is melted and poured into place, at which point it becomes transparent/translucent.

Image above of E-Z Water being poured into scenery, captured from linked site.

The site offers coloration/tints for the products as well, with cautions regarding one set of colorants to not be used with a specific set of water products, alternatives provided in the product text.

Based on the other comments, I would expect there is a PVA component to these products.

That's $17.99 for 472mL, or $173-ish for a gallon: more than twice as expensive. — Joachim, Feb 23 '23 at 21:30

score 1 · Answer 4 · answered Feb 25 '23 at 19:34

Depending on the nature of the diorama that you're making you create the perception of depth (For example, in a river), by painting the riverbed 2-3 shades darker than normal, and then using 2-3 coats of clear varnish to create a thin transparent layer (Or simply a thinner layer of resin).

I use this method but with photosensitive resin rather than epoxy, as it's easier to get the bubbles out.

What are some inexpensive alternatives to epoxy resin for diorama water effects?

4 Answers4