Forum latest

How-To: Custom Epoxy Shapes
Written by Booman   
Saturday, 09 December 2006 16:49
Article Index
How-To: Custom Epoxy Shapes
Project Description
Clay Forms
Clay Forms Cnt'd
Making the latex mold
Supporting the mold using plaster
Supporting the mold using clay
Preparing and making the cast
Releasing the cast
All Pages

Custom Epoxy shapes

Ever wanted to build a custom ice-themed case like this, but just couldn't quite figure out how to make the little bits of plastic that would really set it off?

If so, read on and learn a way to make the little bobs and nubbins that will transform that ho-hum case mod into something that will really turn heads!

(Click on any image to get a larger view)




To create any custom shape to enhance case mod themes by casting 3-dimensional shapes that can be sanded, cut, painted, and drilled into for mounting.

Materials needed:

  1. Clear Casting Resin Epoxy (craft store)
  2. Resin Catalyst (craft store)
  3. Plasticina Modeling clay (craft store)
  4. Mold release or Vaseline (craft store)
  5. Latex Rubber Mold (craft store)
  6. Outdoor workspace
  7. Foam brush (craft store)
  8. Mineral Spirits thinner (hardware store)
  9. Hair Dryer (market)

Total Cost:

  • Casting Resin Epoxy - $14
  • Catalyst - $4
  • Latex Mold - $7
  • Clay - $13
  • Mineral Spirits - $12
  • Plaster - $12
  • (Ed: The pleasure of making that unique case mod - Priceless)



Step One

Begin by rolling some long thick coils of clay.  The easiest way is to roll them on the table under your hand.  They don't have to be pretty because we are going to make them look organic.

Step Two

Next use your thumb and fingers to press into the clay on all sides.  Make it look very bumpy and random looking.  Try not to make any areas too small because they may break later in the final piece.



Step Three

My icicles were made to fit from the inside top of the case to the inside bottom, so I measured them larger than the case (I find it is easier to file them down later for fitting). If your shape needs to be smooth then you can use the mineral spirits and a brush to smooth the clay down.  The clay is oil based and the mineral spirits is a thinner for oil, so it works perfectly.  Try not to get the mineral spirits on your hands.

Step Four

Now lay the clay piece over something that the latex won't stick to after it dries.  This surface should probably be plastic (that's why I used a plastic bag).



Step Five

Make sure to mix up the latex for the mold if it has separated.  Usually the water will go to the bottom of the container and you can't see the separation.  Stir the latex well and then start painting it over the clay piece.  Start with a very thin coat and before it dries paint a thicker coat over it.  The thickness of each coat isn't too important because we will keep adding coats.  Use a hair dryer to dry down each coat, but before the latex is completely dry add another coat; the more coats the better.  Latex is great for casting 3-d pieces because it is flexible and will allow undercuts.



Step Six

When you are finished painting allow several days for the latex to dry.  I had to pull the whole piece off the plastic bag to allow the bottom of the mold to dry.  You can tell it's dry when it is a clear-yellow color and it is flexible.

Step Seven

Now that the mold is dry and ready to be casted into, it has to be supported by something so the cast will hold the origional shape.  The latex is so flexible that it will distort the cast.  The best thing to use is plaster.  You mix plaster in equal amounts of plaster and water.  The best way to get a consistant mix is by sifting the plaster into a container of water until it starts to reach the top of the water, then stir.  When the plaster is mixed, wait until it gets like the consistancy of thick pudding.  This makes it easier to form it over your piece.  Now you can just slop it on.  Do it quickly because the plaster will harden quickly.  Allow a few days for it to dry completely.  You will know when its dry because you won't feel any moisture when you touch the plaster.  The other solution for support is to simply form clay around the mold to hold it up.  It really depends on how large your piece is and if it is completely 3-dimensional.



Step Eight

Start by creating long coils and flatening them down. For my icicle I needed to have the middle higher than the ends so the epoxy would be even all the way across.  How ever your form is shaped, make sure that it is sitting even so every facet of the piece will be filled with epoxy, otherwise you will have parts of the cast missing.




Step Nine

Softly press the mold into the clay carrier so it is completely flat.  If your piece is totally 3-d, then make sure to cast it up-side-down so the mold is completely filled with epoxy.  Also if you are using a 3-d piece and decide to use plaster for the carrier, you will have to do a two piece mold so you can take it apart and pull out the latex mold.  Otherwise you will have to break the mold off and it becomes a one time pour.  Make sure to use a release component on the latex mold before mixing and pouring the epoxy.  I use vaseline.

Step Ten

Now for the pour: The best way to measure how many ounces you need is to fill up your mold with water.  Now pour the water into a measuring cup.  It took me a while to find a measuring cup with ounces on it, but I eventually did.  Next the mixing begins.  WARNING: Tthe epoxy smells really bad and you shouldn't breath it, so either do it in the garage with a mask on or do it outside quickly. For this step you need to have the catalyst (this causes the epoxy to harden).  I looked up some directions on the Castin-craft website and they explain the mixed very clearly with lots of detail.  Start by pouring the amount of Casting Resin ( in ounces you measured when using water) into the measuring cup (cup will not be usable afterwards).  It may be smart to pour an extra ounce just to make sure you don't comeup short.  Then add the appropriate amount of catalyst drops per ounce and start stirring.  For the stirring you should use an object that can be thrown away when done.  Stir the epoxy for 1 minute while scraping the sides and bottom of the cup.  After one minute pour the epoxy into a second container of your choice (it will not be usable afterward) and stir for one more minute.   The reason for mixing it so thouroughly is because any portion of the epoxy that doesn't mix with the catalyst will end up soft and sticky.



Step Eleven

When the epoxy is dry to the touch you can start peeling the latex mold off.  I found that the latex comes off fairly easy but don't force it.  Some of my latex molds were stuck to the epoxy because the resin wasn't completely dry where it was in contact with the latex.  So after peeling the latex mold off I laid the Epoxy out to dry some more.




Here are all of my final iciles and a sabertooth tiger.  I'm pretty happy with the results except for some fingerprints that came out int the epoxy.  Some of them also were not as clear as I first expected but they worked well with the ice look.  If you want them totally clear, then mix some more epoxy and paint on a thin coat over the top and allow it to dry again.

Discuss this article in the forums!

Don't Click Here Don't Click Here Either