Blending like this is a tedious process, and requires much iteration. Even when care has been taken, small lumps may still remain which will result in patches of white (assuming the blend is pigmented) on the final product.
- Chemical blending – this is more expensive, but also ensures fewer iterations and more uniformity in the blend. A range of chemicals is available for this process – but the basic principal is to have a liquid aid with a lower surface energy than PTFE. This will allow the pigment to flow in between the PTFE molecules so that even the lumps are suitably coated with the pigment.