Mar 2, 2014

Rigid and flexible molds for Polymer Clay

I use both rigid and flexible molds. Flex molds are becoming so popular and they are certainly easy and fun to use. One or the other may not necessarily be better  however. Depending on use, a rigid mold can sometimes give better and cleaner results. The rigidness of a mold allows for more control and prevents the design being molded from getting stretched and distorted. Flexible molds are great for when the item is rounded, like a button for instance. Rigid molds are impossible to use for a rounded object like a sea urchin that has a bit of a curved underside. In this example you can see the advantage of being able to stretch a mold to pop out a 3 D item, without distorting the curvature and details and you can virtually turn the mold inside out.
Flexible molds do have their limitations however, in that it is difficult to create texture plates with them. If one has a large surface area to cover such as creating a 4 x 5 sheet, for example, it’s pretty much guaranteed that one will either end up with an unevenly textured piece, that is some areas will be more deeply impressed and others not enough and some of the details may look stretched. Even if one is successful in creating a texture plate with silicone rubber, creating a positive from such a large mold is difficult as the rubbery texture will shift and distort the image you are trying to copy. Another limitation with the flexible nature of such a mold is that if you are trying to create an equal front and back for a pendant, the stretchy nature of the mold might cause one to end up with 2 slightly different sized pieces.
Here is a short version tutorial on how to create a 2 sided item using a rigid mold.
clip_image002 Materials: 
  • Polymer clay such as Fimo which is my new /old preference, but you can use any of the polymer clay brands.
  • · Tissue blade
  • · Rigid mold made from polymer clay
  • · Water
  • · Soft or absorbent brush, or small spray bottle for water
  • · Rubber chisel blending tool
  • · Needle tool
  • · Small metal spatula or exacto knife
  • · Texture such as coarse sandpaper or rough craft foam
  • · Small textured bead or stamp to hide seams
clip_image004 Step 1: Spritz or brush your mold with water. If you are going to use Fimo to cast from the mold, then do not use water as it will make the Fimo sticky. Use corn starch instead.
clip_image006 Step 2: Condition clay, roll into ball and press into the mold. Starting in centre of clay press outward to edges of mold.
clip_image008 Step 3: Use tissue blade starting at about centre of mold and slice away excess. Use the edges of mold as a horizontal blade guard or as an indicator of how much excess to trim. Hold the blade as horizontal as possible as not to slice into the mold. It’s kind of like slicing multi levels of colour clay for mokume gane.
clip_image010 Step 4: Turn the mold 180 degrees and slice away clay excess on other half.
clip_image012 Step 5: Using your thumbs, push the clay toward centre of mold or away from the edges of the mold.
clip_image014 Step 6: To remove the clay from the mold, press onto coarse sandpaper or a coarse craft foam texture.
clip_image016 Step 7: Mold should lift away, by causing the clay to stick onto the texture, but if it doesn’t…
clip_image018 Step 8: …you can also use a small metal spatula or needle tool to carefully lift the edges up and then the molded item is easier to remove.
clip_image020 Step 9: Create another piece as before and then mount the 2 pieces together matching the edges.
clip_image022 Step 10: With a rubber chisel tip you can easily blend and smooth seams. You can also use your fingertips to gently pinch the largest seam together first and then use the rubber chisel for the finer details.
clip_image024 Step 11: Seams won’t then have any of the texture. To camouflage you can create a similar texture by using the sandpaper to impress a little bit of texture over the seam, use part of the mold itself, or…
clip_image026 Step 12: If you have any metal beads with an interesting texture that matches, you can use this as a roller on the seam.
clip_image028 Step 13: This pendant is done. All it needs is a hole for stringing and a bit of colour. One of my favourite method is to use mica or metal pulver on black for an antique metal finish. Of course you can choose any colour you like.
Find my latest molds, both rigid and flexible in my Etsy shop

I’ve added a variety of molds to my shop including this Raven Thor Hammer Pendant mold. There is another hammer, a Sea Horse, Mermaid, Egyptian Themes and much more. I’ll be adding more tonight!


Skyline Spirit said...

pretty nice blog, following :)

Caroline Heinrichs said...

|OMG, don't stop blogging. I just found your blog and would love to learn more. I made a trade with a freind of mine and got this bunch of beads, but need to learn how make my own beads.

This is a great way to make something special.Thanks so much!

Maisie from Oz said...

Tina, you have been more than helpful to me and I want to thank you but also to tell everyone how generous you are sharing your knowledge with everyone.
One look at your lovely work and ideas, leaves me excited and eager to achieve. I hold my breath (almost) waiting to see what eventuates. Thanks Tina

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