Casting Resin in Layers

[RESPRiT]

I've been curious about how one would (if they could) go about making resin caps that are multicolored in layers. Couldn't find any good answers on here or Google, so does anyone here have experience with this?

[Findecanor]

I don't know how the keycap makers do it, but having cast in other resins before, I think it is simply about pouring differently tinted resins one after the other.
If you use epoxy, then you can let one layer cure before pouring the next. Urethane would be more difficult because a new batch of urethane will not bond to cured urethane.

[RESPRiT]

How does the color look if you pour in a different tint before the first tint has cured?

[rowdy]

I'm totally guessing, but could you introduce a little glue or something between layers?

[Matt3o]

cast the first layer, wait until it is slightly cured but not completely, add the second layer, repeat until satisfied.

the curing time depends on the resin you use. I use very long curing time epoxy resin and I can apply a second layer after a couple of hours. The first layer is still gummy, but solid enough to sustain the overlaying layer.

the keycap is ready in 8-10 hours

[damorgue]

The only real issue you have is the joining of the two casts. As has been stated, some materials don't bond to their cured form. Some will disdolve into each other to some extent. There is the possibility to seal the previous layer with a coat of something, eg primer. Depending on how much you let the previous cast cure they might stick or dissolve into each other as well. The only thing that can be stated with certainty is that it will depend on the compounds being cast.

[nubbinator]

cast the first layer, wait until it is slightly cured but not completely, add the second layer, repeat until satisfied.

the curing time depends on the resin you use. I use very long curing time epoxy resin and I can apply a second layer after a couple of hours. The first layer is still gummy, but solid enough to sustain the overlaying layer.

the keycap is ready in 8-10 hours

And it's a fickle beast to do so.  Expect to get less than perfect results more than a few times when trying it. 

[Matt3o]

guys you are using the wrong compounds.

take very long curing time resin! Mine needs 8-10 hours to cure. After 2 hours it becomes jelly and sticky. The end result is seamless.

The problem is that you can't have layers of the same height (or at least it's very hard to do). The last one (the one near the bottom of the cap) needs to be taller.

[RESPRiT]

guys you are using the wrong compounds.

take very long curing time resin! Mine needs 8-10 hours to cure. After 2 hours it becomes jelly and sticky. The end result is seamless.

The problem is that you can't have layers of the same height (or at least it's very hard to do). The last one (the one near the bottom of the cap) needs to be taller.

Could you elaborate on the layer heights?

[Binge]

I'm curious as to why the OP is not/can not/will not experiment with materials he can source :|

Not everyone has access to the same materials and they each behave differently.

[RESPRiT]

I'm curious as to why the OP is not/can not/will not experiment with materials he can source :|

Not everyone has access to the same materials and they each behave differently.

I don't have any materials yet Binge I will definitely experiment once I do get some molding silicon and resin, though.

[Binge]

I'm curious as to why the OP is not/can not/will not experiment with materials he can source :|

Not everyone has access to the same materials and they each behave differently.

I don't have any materials yet Binge I will definitely experiment once I do get some molding silicon and resin, though.

Good!  You will learn the most that way, people will be able to suggest techniques and you will be able to really take it in because you would have a small background of experience

[Pac Caps]

I'm curious as to why the OP is not/can not/will not experiment with materials he can source :|

Not everyone has access to the same materials and they each behave differently.

I don't have any materials yet Binge I will definitely experiment once I do get some molding silicon and resin, though.

Good!  You will learn the most that way, people will be able to suggest techniques and you will be able to really take it in because you would have a small background of experience

Are there good guides for this kind of work?

[RESPRiT]

Here are a few links I have saved:

http://geekhack.org/index.php?topic=50780.0
http://geekhack.org/index.php?topic=23722.0
http://geekhack.org/index.php?topic=41371.0

[Binge]

I'm curious as to why the OP is not/can not/will not experiment with materials he can source :|

Not everyone has access to the same materials and they each behave differently.

I don't have any materials yet Binge I will definitely experiment once I do get some molding silicon and resin, though.

Good!  You will learn the most that way, people will be able to suggest techniques and you will be able to really take it in because you would have a small background of experience

Are there good guides for this kind of work?

tons and tons.  Google search for "how to cast a two part mold" yielded great results

[nubbinator]

Here are a few links I have saved:

http://geekhack.org/index.php?topic=50780.0
http://geekhack.org/index.php?topic=23722.0
http://geekhack.org/index.php?topic=41371.0

I also have this thread in addition to my other.  I go a little more into some of the successes and failures and need to do some new updates with different resins.