It's easy to focus on the cap shell and forget the part that actually seals: the wad, the thin liner pressed inside the cap top. Choose it well and the bottle holds its seal through transport, storage and shelf life. Choose it poorly and you get leaks, evaporation or contamination — no matter how good the shell is.
EPE (expanded polyethylene) is a light foam liner. It's clean, cost-effective and a strong all-round choice for water-based products — syrups, tonics, many food and beverage fills. It compresses to take up neck-finish variation and gives a reliable, food-safe seal.
Latex liners are flowed into the cap and cured to form a gasket that hugs the glass finish. They excel where you need a tighter barrier — spirits with higher alcohol content, or products sensitive to evaporation.
GSR Metal Caps supplies every ROPP size with your choice of EPE or latex wad. Not sure which fits? That's exactly what free samples are for.
