dyeing resin

[Matt3o]

I did some experiments with resin casting in the last months and I tried epoxy, polyurethane and polyester resins. Epoxy is probably the easiest to find and use but IF (and it's a big if) you can find the right polyurethane it's definitely the best.

Polyurethane resin is quite common among modelers to make dioramas and figurines and it usually comes in a two compounds that mixed together make a beige paste. That's fine because they prime and color the resin afterward. I need instead the resin itself to be of the right color.

Dyeing a beige resin is a no-no (tried it...). So, after quite a research I've found a clear polyurethane resin that I can easily source over here. The problem is that I can turn it to a translucent color (similar to translucent polycarbonate) adding up to a max of 3% of colorant. Adding more makes the cast less stable, so I'm wondering if you have any idea how I could make a solid color. Are there "pure white" polyurethane resin (I couldn't find)? Or maybe some special colors I can use?

thanks

[nubbinator]

You can dye beige resins.  How to dye a resin is entirely contingent upon the type of resin used.  Some resins will take powders of different types, some do well with alcohol inks, and some have thick liquid dyes that work well with them.  You have to experiment with a bunch of different things and find what works with your specific resin.  That's what I've done.;  I've dropped hundreds into different things to try, some successfully, other's catastrophic failures (like some drafting inks I tried that were supposed to be in alcohol, but apparently weren't).

If you don't want to experiment, go with either Smooth-On or Alumilite resin and the dyes/pigments they sell for their specific resin.

[Zekromtor]

With epoxy you can mix in some powdered solid to remove the translucency, steel or aluminum for example, you can probably do the same with poly. Some nice white stone powder or calcium carbonate should do the trick for you. Here's some info on resin fillers
http://davidneat.wordpress.com/materials/casting/common-fillers-for-resin-casting/

[Matt3o]

You can dye beige resins.

you can but you get very unsaturated / brownish colors.

With epoxy you can mix in some powdered solid to remove the translucency, steel or aluminum for example, you can probably do the same with poly. Some nice white stone powder or calcium carbonate should do the trick for you. Here's some info on resin fillers
http://davidneat.wordpress.com/materials/casting/common-fillers-for-resin-casting/

wow, very interesting post.

I believe polyurethane is a little more picky regarding what you can actually mix with it, but I'll give it a try.

I've found a "softening" agent for epoxy, maybe I could add just a pinch of it to make epoxy less brittle (more ABS like). If you add a lot of it you can actually have bendable objects.

[nubbinator]

You can dye beige resins.

you can but you get very unsaturated / brownish colors.

Not really.  I've used beige resins and gotten good results.  You might be using the wrong pigment or dye or not enough.

[Matt3o]

You can dye beige resins.

you can but you get very unsaturated / brownish colors.

Not really.  I've used beige resins and gotten good results.  You might be using the wrong pigment or dye or not enough.

probably not enough but I'm always worried of putting too much. or maybe the resin I used is more beige than yours (it's more like a light brown actually)

[Findecanor]

Polyurethane resin is quite common among modelers to make dioramas and figurines and it usually comes in a two compounds that mixed together make a beige paste.

Paste? The ones I have seen (and used) have been liquid. It needs to be mixed and poured quickly before it starts to set. If yours is brown and thick then I suspect that it would already contain some filler.

I have seen some resin objects that have been whiter than others, but none that is pure white.
You could use powders, but the more powder you add the more brittle the result will be.

You could also powder the silicone mould with the powder and shake off the excess before pouring the resin. I have made metal-looking casts this way that look better than if I had used metal paint but the surface is not very durable.

[Matt3o]

Polyurethane resin is quite common among modelers to make dioramas and figurines and it usually comes in a two compounds that mixed together make a beige paste.

Paste? The ones I have seen (and used) have been liquid. It needs to be mixed and poured quickly before it starts to set. If yours is brown and thick then I suspect that it would already contain some filler.

well, let's call it thick liquid

I couldn't find pure white poly, but could find pure white epoxy. I'm going to try that with just a pinch of "flexibility" adder. I believe it's the same used to make flexible pencils

[Zekromtor]

Keep in mind that these "pure" white epoxies are probably just epoxies with various fillers. If they are super expensive you can always consider mixing your own stuff. I wonder if you could achieve results like that with rubber powder.

[Matt3o]

it's not considerably more expensive than clear resin, I'd say +€2.50 per kg

[Zekromtor]

Well then it's probably worth it since mixing is probably a pain. Let us know how it turns out.