Sponge where the closing force is low
Sponge is chosen when the lid or door cannot deliver much force - light gauge packaging equipment, inspection covers, and panels that a person opens by hand. The cell structure closes under low load and still fills the gap, which a solid profile of the same size would not do.
Density is the decision that matters
Density sets the closing force, the compression set behaviour and how the material recovers after repeated opening. Pick it against the force your closure actually delivers. Too dense and the lid will not seat; too soft and the gasket takes a permanent set.
Closed cell versus open cell
Closed-cell sponge resists liquid and vapour ingress; open cell does not. For washdown areas and wet product, closed cell is usually the right call. It is worth stating explicitly because the two look identical in a photograph.
Cleaning and temperature
Steam and caustic cleaning are the usual failure causes, not the product itself. Give us the cleaning cycle and the temperature range and we will recommend a compound that has been documented for both.
Cut to length and joined
Sponge gaskets are usually supplied cut, mitred and joined into a frame, with adhesive backing where the part has to stay put during assembly. Send the frame drawing and we will quote the finished part rather than the length.
Profiles for this application
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Working on something like this?
Send the drawing, cross-section, operating temperature and what the seal has to resist. We will tell you whether a stock profile fits or the part needs extruding, and quote both.