Last modified by Hypno Harem on 2022/07/19 16:43

Delamination is the separation of two layers of silicone from each other. Any place where silicone is poured at different times, in different materials, or with significantly different pigment loads; there is increased risk of delamination. The root cause is poor chemical adhesion when layers are poured at different times, or the creation of a stress riser when using different materials or different pigment loads. This is not an issue seen with fades or marbles where the silicone is poured together. Only when there is a hard break going from one area to the next such as in drips and splits.

Delamination is easy to avoid by developing and following a known, repeatable procedure. When first doing drips and splits, perform a scratch test and a stretch test where you have purposely exaggerated the root cause. Examples would be letting the first layer on a hard split cure for an hour and a half before adding the second layer when your usual turnaround time is only 45 minutes, adding silicone thinner to 00-30 to use as a split layer with 00-50, or adding a larger-than-planned amount of pigment for a colored drip over a translucent material. Note that you should try to use the materials you actually plan on adopting for manufacture. Doing a stretch test with 00-20 split to 10A will have a greater stress riser than 00-30 to 00-50, but you may be introducing new issues unrelated to the actual planned pour.

This kind of flaw is normally treated as a turbo flop when discovered, and toys are either destroyed or marked as not for resale. Even small peeling areas can hint at a serious underlying risk of an entire toy suddenly ripping in half.

Image shows small area of delamination starting on a toy

Image shows progression of delamination when toy was stretched

True delamination can progress rapidly. The tear will be between layers and will not usually leave any of one layer on the next. Above shows what propagation of delamination looks like. If yellow silicone had been left behind on the silver area; this would possibly be normal tearing through the bulk silicone, possibly enhanced by a the change in material properties going from one color to the next and would be less of a concern. Since this left behind a clean surface it was identified as delamination, and the process causing it was modified to lessen time between layers and remove the root cause.

To eliminate the risk of delamination:

  • Perform scratch and stretch tests if a process is new to you to establish your process boundaries
  • Work quickly and only allow layers to cure as much as is absolutely necessary to achieve the desired result
  • Never leave a split or drip overnight before completing the pour
  • Do not split Dragon Skin 10NV with EcoFlex materials
  • Do not use mold release in the workshop without proper ventilation while drips or spilts are being processed

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