Are your Silicone Products 100% Silicone? – Find out with the Pinch Test

Not All Silicone is Created Equal.the pinch test for silicone fillers

The Pinch Test: an easy way to test for fillers in silicone. Pinch, twist, or pull silicone. If it turns white, it has fillers. Otterlove products will ALWAYS pass The Pinch Test because they are made with 100% silicone with no fillers.

Don’t be fooled by other brands’ claims that they are 100% silicone without fillers. Many brands claim to be 100% silicone because they have passed an FDA food safe test, but this test does not determine if there are fillers in the silicone.


A key item to note in these standards is that Silicone products are allowed to have impurities or fillers as long as they stay beneath the “safe” levels. Simply put, “food safe” silicone can still have fillers in it.

May brands put in fillers in their silicone because they are cheaper. They can do this as long as they can stay within the bounds of the FDA testing requirements. FDA tests are less strict than European testing (such as LFGB). This practice occurs with both US manufacturers and overseas manufacturers.

Many brands also claim that they pass the pitch test, but they do not. Thicker silicone items, like cups and plates, need more force to see the fillers whereas a thinner product, like a silicone bib, can be lightly stretched to see the impurities. 100% pure silicone should never change color when you twist or pinch it.


Beware of Brands that say the Pinch Test is “Unscientific”

Some brands say The Pinch Test is not “not scientific”. This is not true- be wary of any brand who says this- sadly, they are trying to sow doubt in consumers’ minds in order to increase their profit through using cheap silicone with fillers.  The science behind the Pinch Test is simple, as noted in this Scientific American article. Because of its structure, pure silicone absorbs light and appears transparent. Fillers added to silicone do not have the same band structure as silicone, so they cannot absorb light as pure silicone does. These impurities scatter light and this is the white you see when you do the Pinch Test on silicone that contains fillers.

Here are some additional supporting quotes from leading Silicone Manufacturers:

If we use a pure platinum-curing silicone rubber from one of the big manufacturers listed above, it will NOT turn white when stretched (regardless if it is injection molded or compression molded). In our opinion, a clear silicone will turn white only if a precipitated filler is added to it. If the silicone turns white when it is stretched, I would be wary of using this product…only because you know something was added to it.” – Specialty Silicone Inc. interview  (available at:

I have never experienced any silicone that has changed color when pinched, pulled, twisted or stressed in any way.  Again, this is something that occurs with natural rubbers like TPE.” – Wacker Chemical Corporation interview  (available at:

Fillers are less expensive than Medical silicone.  HCR (High Consistency Rubber) is frequently loaded with filler that does turn white when pulled.” – Casco Bay Molding (available at: