Material choice is a specification decision, not a finishing detail. A four-piece set from four suppliers feels like four products in the buyer's hands, and the complaint lands on the wrong part.
Fix the family before the SKU list
Three families cover most strength and mobility sets: TPE for mats, bands and small moulded goods, PVC for dense blocks and sliders, EVA for foam blocks and wedges, with silicone alongside for grips and coated weights where skin contact dominates. Pick one dominant family, allow one documented exception, and write the reason onto the specification sheet so the question is not reopened at sampling.
What a consistent feel measures
- Shore A inside a stated window, measured on the finished part rather than a datasheet.
- Rebound and compression set after repeated loading; parts that recover at different rates feel mismatched even in matching colour.
- One surface target for the whole set: matte, satin or embossed, at the same roughness figure.
- Colour from one masterbatch system, so two parts in the same reference do not separate under store lighting.
Two materials, two failure modes
PVC is still right for dense blocks, but it brings plasticiser migration that marks dark lacquered furniture, shrinkage after heat in transit, and a glossy skin that turns slippery wet. Specify plasticiser type and loading, request a staining test on a lacquered panel, and add a dimensional allowance for container heat. A care line on the packaging beats a claim.
On EVA blocks, density is the honest signal: under roughly 60 kg/m3 a block dents under a thumb and loses corners within a season, while 80 to 110 kg/m3 reads solid without feeling like a brick. A sharp moulded edge chips, a radiused edge survives. Ask for a corner drop test and 24-hour loaded deflection on the same sample.
Print, freight and classification follow the material
Pad printing adheres differently to TPE, PVC and EVA, so a logo that passes a tape pull on a mat can fail on a foam block: require an adhesion test per substrate, keep one ink system, and deboss where print would land on a compressible face. Density drives volumetric weight, and classification follows the article and its material, not the marketing name, so confirm the code in writing before sampling. The published overview of the thermoplastic elastomer family helps when TPE is used as a loose label for several compounds.
Checklist before tooling
One document should hold the family decision, hardness window, finish target, adhesion result and classification code, reviewed against daylight samples with every part on one table. Our customisation process starts from that document, and compound qualification before a run is described on our about page.
Frequently asked questions
Should one set use a single material family?
Yes, one dominant family with at most one documented exception. Buyers notice a mismatched rebound or finish long before they notice a material name.
Which EVA density feels premium in the hand?
Between 80 and 110 kg/m3 with a radiused edge. Below 60 kg/m3 the block dents under thumb pressure and corners fail within a season.
Does material choice change duty classification?
It can, because classification follows the article and its constituent material rather than the product name. Confirm the code in writing with your forwarder before sampling.
Why do logos fail on foam but pass on mats?
Ink adhesion differs per substrate and foam compresses under the pad. Run a tape pull test on each material and switch to debossing where print cannot hold.