@daniel_bohrer Yep, actually there are two types of glues for Latex: Latexmilk / Liquid Latex and Vulcanizing Adhesive. Both must be applied to both sides and then let dry before sticking them together. The former creates a new layer of Latex on the garnment while the latter somehow liquifies the existing rubber allowing it to bond with the other side to form a homogenous rubber seal. The latter is the same method used for fixing bike tubes.
The former is preferred for thinner latex (<0,4mm) and the latter for thicker sheets because it makes the rubber warp more.

Here I had no rip in the latex but only an open seam because Libidex did a shitty job (not the first open seam with these pants). So I just redid the seam.

When the rubber is ripped you need to put a patch preferably on the inside that covers the area around the rip. When done professionally it's almost invisible.