9

I am looking for an alternative to resin to fill a series of jars with, that will harden solid.

My aim is to make it appear as if the jars are filled with an opaque liquid that could pass for some kind of generic produce at a distance (milk, jam, table sauce, etc.).

I intend to put a tube in the center of each jar to create a chamber, and then fill the space between it and the side of the jar with "something" colored to make the jar seem full, so that you can take the lid off of the jar and put a model or miniature diorama inside and let it be hidden until the lid is taken off (For example, a jar of honey containing a model of a bee).

The normal go-to for this is epoxy resin, but I don't have the budget or ventilation required to use resin on this scale (and it's far too messy), so I'm looking for a cheaper and safer alternative, like a plaster compound or something.

It needs to be non-toxic, set solid, and to be able to be colored so that it's opaque, but does not need to be particularly durable.

I have considered simply painting the inside of the jars but it just looked like a flat surface and didn't have that slightly translucent look that you would get with a liquid that you can achieve with resin.

6
  • 1
    Painting sounds like a logical solution. What was its shortcoming that you need to correct (that would be fixed by a thin wall of something solid)?
    – fixer1234
    Oct 24 at 16:21
  • Painting the inside of a jar cleanly and without getting brush strokes is difficult, and failed to accurately replicate the effect of a liquid. Oct 24 at 18:19
  • Is this for long-term use or short term?
    – Chris H
    Oct 25 at 7:53
  • 2
    Very closely related: Crafting "fake potions" where I suggest gelatine if it doesn't have to last forever. You can mix it with milk to be opaque. Others suggest candle gel as well as epoxy.
    – Chris H
    Oct 25 at 7:57
  • 1
    What kind of paint did you use in your (failed) test? There are some more translucent paints available that might work better for you (glass paints, glazes, etc).
    – Allison C
    Oct 26 at 17:18
10

You can make a firm gel using agar mixed with hot water. It's clear, colorless, nontoxic and is actually edible. It looks like Jello after it sets, but it doesn't melt at warm room temperatures. You can color it with ordinary food coloring. It's much less expensive and safer than casting resin.

5
  • One potential problem is that mold and other microbes can grow in agar. It might be possible to add something (maybe lots of salt?) to it to make it less hospitable for micro-organisms, but at least I don't know of a good recipe for that off the top of my head. Oct 25 at 18:01
  • 4
    @IlmariKaronen Mold and microbes grow on nutrient agar, which is a mixture of water, agar and nutrients (sugars, proteins, electrolytes, etc.), but plain agar gel is not very supportive of microbial growth. I've made long-term stable agar gel with all microbial growth inhibited by adding 0.2 grams of sodium azide per liter of solution, but this is a toxic chemical and I don't recommend using it outside of a laboratory. OP might try plain agar gel and see how it lasts long-term before considering microbial inhibitors.
    – MTA
    Oct 25 at 20:55
  • @MTA I wonder about a little household bleach as an inhibitor. That's familiar and not very toxic
    – Chris H
    Oct 26 at 8:10
  • 1
    @ChrisH it is however dangerous because of unexpected chemical reactions (you can google bleach+ammonia, if you're not on a watchlist, but don't try it)
    – user253751
    Oct 26 at 8:14
  • 1
    @user253751 it reacts badly with a lot of things to produce chlorine. Ammonia is one of the worst because it forms chloramine instead (at least with chloramine you'll want to get away at the first sniff). A few drops in gelatine will be safe, though 2.5% NaOCl will dissolve gelatine (I can only see the abstract at the moment.
    – Chris H
    Oct 26 at 8:23
9

A fairly easy solution would be to use candle wax. This can be melted and coloured then you can either fully fill the vessel or apply as a thinnish layer to the inside of the glass to create the look you want. If you did go for the thin layer around the vessel, then it should be possible to subsequently partially fill with water then apply a thickish layer on top to space fill and keep the contents in.

8

Paint that's fairly compatible with the material of the bottle can be applied evenly by pouring it into the container, swirling round and tipping out. You may need to do this 2 or 3 times. This should mimic milk fairly well. PVA could be applied similarly.

For a clearer filling you could use coloured varnish instead, but this wouldn't really look like jam, as that's solid throughout the container so refracts light different.

If your inner vessel is very close to the size of your outer vessel, you won't need much filler, so epoxy wouldn't be so expensive after all

8

Would it be possible to do this with sugar?

If you boil a heavy sugar syrup enough it will set hard and clear, almost like glass. I accidentally filled a bowl with brown "glass" and bits of orange this way, and it was almost impossible to get out.

Sugar is cheap and doesn't need special ventilation, but you do need to be very careful handling hot syrup.

3
  • Sugar will attract ants. Oct 25 at 18:13
  • 6
    Please be very careful when handling hot sugar. Some glasses might break if they are heated suddenly and unevenly, like when you pour molten sugar into one side of it and leave the other side empty. Getting molten sugar onto your skin or clothing can cause disasterous buns because the liquid is much hotter than boiling water, takes much longer to cool down, and sticks to you.
    – Elmy
    Oct 26 at 4:49
  • 1
    @Elmy I'd preheat the vessel by putting it in a cold oven then turning the oven on to a temperature not much less than that of molten sugar. That would avoid stress cracking. I do something similar to sterilise jam jars.
    – Chris H
    Oct 26 at 8:11
5

An alternative to the agar gel in MTA's answer is a gelatin and glycerin mix.

  • The basic recipe is food safe and often used to make molds for food items.
  • You can store it in a freezer for months (without any additives).
  • The basic recipe will keep fresh at room temperature for several weeks. You can add things like honey or citric acid to protect it from mold growth for a longer time.
  • It's reusable. You can simply melt the gel by heating it up.
  • You can mix it with food coloring, naturally colored liquids like honey or powders like corn starch (for a milky look).

The basic recipe uses 2 parts powdered gelatin (sugarless; not the sheets), 2 parts glycerin (from a drug store or pharmacy) and 1 part water. Soak the gelatine powder with the glycerin for 5 minutes, mix in the boiling water and strain it once (most of) the gelatine is molten. Do not boil the mixture or you destroy the gelatine.

You can see a video of the basic recipe here and an instructable for making moulds and prosthetics here.

4
  • Wouldn't this go mouldy? Oct 26 at 17:00
  • Eventually, it would either dry out or go mouldy, but depending on your climate that can take several weeks. If you store the gel in a fridge or freezer, it keeps for half a year. Mixing honey or citric acid into the gel also protects it against mould.
    – Elmy
    Oct 26 at 17:20
  • I had considered to recommend gelatin but was unsure of the lifespan. Ballistic gelatin may have a longer life but might also discolor over time. Considering the low cost of the materials, it's a good option for experimentation.
    – fred_dot_u
    Oct 26 at 17:45
  • @AaarghZombies, there are various recipes. Some use little to no water and will be less susceptible. You can also add a few drops of various materials that inhibit the growth of mold and bacteria. It's not a "permanent" material, but the right recipe could last a long time in a jar that is usually closed. It isn't clear if "durable" in the question refers to tough or long-lasting. It will help people answer with appropriate solutions if you edit the question to clarify whether the material needs to last a long time (Chris H's question in a comment).
    – fixer1234
    Oct 26 at 18:36
4

PVA glue is available in white, yellow and clear varieties. I've had the white and yellow stuff set up (cure) in bottles and remain liquid appearance, but have not used the clear stuff to know what happens over extended time.

The white and yellow glues are inexpensive and water soluble and will take common food coloring to achieve various colors and hues as desired.

For the purposes of the description, if the glue sets/cures in the jar, it won't affect your desired results, as it still appears to be liquid. If it is partially filled, the top surface also appears to be liquid.

2
  • 1
    PVA glue will cure in the bottle, but it takes forever. A wall of it around a jar that must dry out from the edge will take a very long time (weeks to months). And until it's fully cured, the part that's still liquid will look different from the part that's cured. But this will work if time isn't an issue.
    – fixer1234
    Oct 24 at 22:33
  • It does seem like forever, until one goes to use the glue only to discover that it has set up. "I'm sure I used it just last week" doesn't fly, though.
    – fred_dot_u
    Oct 24 at 23:48
3

In addition to the existing answers, you can also use acrylic paints.

There are translucent paints (or (mix them with) mediums or gels), they are inexpensive, will set quite rapidly (if sufficiently exposed to air), you can mix in other materials (e.g. for an imitation of jam you can add blobs of pre-dried and somewhat darker coloured acrylics), and they are usually relatively non-toxic, especially after drying.

To fill the jars, you can first pour in some acrylic paint, then, while holding a somewhat sturdy plastic sheet the size of the inner container, pour in the rest along the edges.

1
  • 1
    Acrylic would be a good choice of paint for my suggested method on most materials, +1
    – Chris H
    Oct 26 at 8:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.