How to dye or tint epoxy resin to produce translucent colors?

Question

A while ago I started crafting with epoxy resin. At first I just coated objects with clear resin, but recently I experimented with adding colors to it.

I got nice results with powders (like glittery eye shadow) and a tiny bit of acrylic paint, but the result always loses the crystal clarity of the resin and gets somewhat cloudy or opaque.

Next I bought transparent liquid glass paints in the hopes of mixing a more transparent but colorful resin. But to my surprise the color didn't mix with the resin at all and instead formed tiny flakes of (still liquid) color in the otherwise absolutely untinted resin. The effect is not bad, but not at all what I wanted.

The glass color was water soluble, but probably not acrylic paint. It didn't say exactly what was in there on the packaging.

My goal is to find something that will tint the resin but keep it translucent. If I go shopping in my craft store, how do I know which colors will mix with epoxy resin without having to buy a bunch of material for experimentation and ending up not using most of them?

I'd appreciate general answers like "acrylic paints mix well but oil paints don't" instead of naming specific brands of paints that might not be available where I live.

Since I got the best results with powders so far, I thought about buying high quality aquarelle paints (the solid blocks) and grinding them into powder, but I'm afraid the resin will get cloudy / opaque again and the money will be wasted.

Answer 1

You need something that's soluble in the liquid epoxy, or possibly a liquid that's miscible with it. Water isn't miscible with epoxy, and if you try too hard to mix it you'll produce cloudiness. I suspect that rules out acrylic paints as well. Typical solvents don't dissolve epoxy; some may be miscible. I'm not sure what the liquid phase is to investigate solubility.

Powders in general - unless you want a glitter or speckle effect - are unlikely to work however fine you grind them.

There are specific dyes for epoxy (Amazon example), and this article also recommends alcohol inks - you can try making your own from old marker pens if you just want a test batch, though I'd use solvent-based markers to start with (such as Sharpies or cheap equivalents). It would appear that alcohols mix with the solvents used in the epoxy components and in fact can apparently be used to thin epoxy.

You may have a little more trouble getting bubbles out than normal - a vacuum system is one way to help with this, but thinning should also help.

Answer 2

I've done this myself successfully with alcohol inks. I use the ones from Ranger; Piñata's inks are likely to work as well.

Avoid Sharpies as they tend to fade and change color over to time. I know this the hard way from having used them with polymer clay. :-(

Answer 3

I found food coloring and acryllic paint to be the cheapest solutions, but certainly not the best. The results remain inconsistent, even with 2 colors of the same package.

Following Chris' answer I used alcohol based food colorings at first, but they are hard to dispense (too liquid, the resin turned cloudy because there was too much liquid compared to the amount of resin) and I usually cannot get alcohol based food colors where I live.

Then I tried sugar based (glucose syrup) food color gels and some of them work, some don't. They have a low water content (less risk of cloudyness) and are easier to dispense. I bought a package of 4 colors: one didn't mix evenly and caused speckles, one mixed very well but turned the resin into goop (it still cured very hard). I haven't tried the other 2 colors yet.

Another downside is that food colors are not meant to last long, so I suspect they will fade rather quickly if exposed to sunlight.

In my tests acryllic colors always mixed evenly with resin, but depending on the formular of the color, the result won't be translucent. Expecially cheap paints contain chalk-like powders as fillers, which will be wisible in the resin. Some paints changed colors quite drastically.

Here's a recent example of my castings and the same colors I used in the resin applied to paper:

From left to right:

1. Blue food coloring. Turned the resin into goop, but cured correctly. The cloudyness is partially intended because I mixed a lot of tiny air bubbles into the goop.
2. Red food coloring (of the same package as 1) didn't mix evenly and caused speckles instead. The color also changed in the resin.
3. Dark red acryllic paint. As soon as I mixed it with resin, it turned into strawberry color. When the resin was cured, it looked more like sunflower yellow.
4. Purple acryllic paint. Mixed perfectly and didn't change color at all.

Answer 4

I'm not sure we're all actually referring to the same properties. Let me start with some definitions.

Transparency refers to light passing through the material without being diffused or scattered. If the material is transparent, you can change its color but still see undistorted detail. Think "looking at the world through rose-colored glasses". Transparent tinting filters the color spectrum of the light that gets through, but the light that gets through does not have the detail degraded.

Translucency refers to light passing through the material but being diffused or scattered. Virtually all of the light makes it through the material, but the direction and relative position get randomized. There are a few common ways of making a material translucent. One is to etch the surface to frost it, which scatters the light direction. Another is to mix two transparent materials with a different refractive index. Light passing through gets bent in random directions (the result looks cloudy). These methods don't significantly reduce the amount of light getting through.

You can simulate translucency by mixing in a small amount of opaque powder. That reduces the amount of light getting through by making the material partially opaque. Some of the light will reflect off the powder particles and make it through the material in some other direction, imparting the powder's color to the mix of light getting through.

From the wording of the question, it sounds like you might be looking for transparent color rather than translucent color (it seems like you achieved translucent color but that wasn't what you wanted). There are many different kinds of resin systems, so unfortunately, it will take some experimentation to get the result you desire with a particular resin. In the most general terms:

• If you want transparent color (the "crystal clarity"), the choice of colorants will be pretty limited. It will have to be a physically compatible, transparent dye material of virtually the same refractive index as the resin. This will probably be a resin dye made for this purpose. You may luck out with something else, like certain alcohol inks, but it will take experimentation to see what works with your resin.

• If your goal is translucent color without opacity, a range of techniques and colored materials can work:

  • Make it a transparent color and frost the resin surface on one side (e.g., via etching or sand blasting with a suitable medium, or cast the resin on a frosted surface).

  • Add a transparent colored powder of a different refractive index (e.g., colored glass dust).

  • Add a transparent dye of a different refractive index. It will need to be something that mixes with the resin, otherwise it will aggregate in visible bubbles or specks. You may also find that if the dye is in a carrier liquid, it can separate in the resin. That can leave blotchy results, where some areas have more pronounced color and other areas are an unattractive cloudy color. You can also encounter strange color changes, where the finished color doesn't look like the dye color.

    Note that the amount of dye can introduce unexpected color changes. A very common one is with yellow. Trace amounts of yellow dye will look yellow. But as you add more, it will look orange or red (it has to do with the spectrum of light being filtered).

  • You can make it cloudy by creating lots of tiny air bubbles, but it is hard to make this uniform or to control the size of the bubbles.

• If you don't mind some opacity and the associated reduction of light passing through, there are some additional techniques available:

  • Make it a transparent color and apply a flat clear finish. What makes the finish flat is typically extremely fine silica (it may be somewhat translucent, but there will be light loss). You would need to experiment with how thick a coating to use.
  • Mix in a tiny amount of extremely fine colored opaque powder, like the eye shadow you tried (which is mostly mica and colorant). You might want to grind it even finer, and mix it in so it is very well and evenly distributed. A tiny amount will impart some color and translucency without too much light loss, but adding more will quickly make the resin opaque.
  • Embed a material that will be translucent. A number of materials will become somewhat translucent when saturated with resin, like tissue paper and some fabrics or fibers. You can get some interesting effects by embedding a thin layer of such material in transparent resin. You may need to remove air bubbles by using a vacuum chamber, or use a process that allows the resin to soak into the material and saturate it without trapping air.

Answer 5

None of these seem like a good and or full answer or response. Neither is this, but I can elaborate if necessary. The best way to introduce translucent color to an epoxy resin pour is to use mica powder. Mica powder is a multiple thinly layered powder and is the answer for adding translucence to your pour. Do not thin, do not use acrylic paint, and if you have bubble issues after you have fully mixed, then use either an extremely expensive vacuum technique (the proper use of which is not common even among many professionals). Rather, use a heat gun and/or a mini propane blow torch. Also, make sure you maintain the ambient temperature indicated by the epoxy. This usually involves a heat source and the ability to maintain the temperature in a room, or creating a "hot box" using a space heater.

Answer 6

For transparent colors I recommend using alcohol ink colors, they stay really transparent but depending on how many drops you add you can get a darker shade Keep in mind adding too much of anything to 2 part epoxy may effect the curing process!