10

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.

Improve this question
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
    Commented Oct 24, 2021 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.
    – Aaargh Zombies
    Commented Oct 24, 2021 at 18:19
  • Is this for long-term use or short term?
    – Chris H
    Commented Oct 25, 2021 at 7:53
  • 3
    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
    Commented Oct 25, 2021 at 7:57
  • 2
    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
    Commented Oct 26, 2021 at 17:18

7 Answers 7

Reset to default
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.

Improve this answer
4
  • 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.
    – Ilmari Karonen
    Commented Oct 25, 2021 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
    Commented Oct 25, 2021 at 20:55
  • @MTA I wonder about a little household bleach as an inhibitor. That's familiar and not very toxic
    – Chris H
    Commented Oct 26, 2021 at 8:10
  • 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
    Commented Oct 26, 2021 at 8:23
10

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.

Improve this answer
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

Improve this answer
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.

Improve this answer
3
  • Sugar will attract ants.
    – user3067860
    Commented Oct 25, 2021 at 18:13
  • 7
    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 ♦
    Commented Oct 26, 2021 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
    Commented Oct 26, 2021 at 8:11
6

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.

Improve this answer
4
  • Wouldn't this go mouldy?
    – Aaargh Zombies
    Commented Oct 26, 2021 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 ♦
    Commented Oct 26, 2021 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
    Commented Oct 26, 2021 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
    Commented Oct 26, 2021 at 18:36
5

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.

Improve this answer
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
    Commented Oct 24, 2021 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
    Commented Oct 24, 2021 at 23:48
4

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.

Improve this answer
1
  • 1
    Acrylic would be a good choice of paint for my suggested method on most materials, +1
    – Chris H
    Commented Oct 26, 2021 at 8:12

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .