Do you mean covering with liquid latex skins? Or casting in foam latex?
Richard Svensson has a lot of videos showing how he makes his monster puppets using soft urethane foam and latex skins to cover them. His Youtube channel is Bluworm: https://www.youtube.com/watch?v=y3b-MrGbwZ0&list=PLwplD2haq8lyW... He is in Sweden, so whatever he gets would be available in Europe.
For this you need liquid latex. It depends on what country you are in, but here in Australia my suppliers stock 2 kinds of liquid latex. Brushable Latex is a bit thicker, Spray Latex is thinner. Sometimes I mix the two together to get something in between, usually to build up over the urethane foam puppet. Otherwise, If I want thin skins I use the Spray Latex. I don't actually spray it, I dab it on with bits of sponge or soft foam. Thin skins let the puppet bend more easily, thicker ones are more suitable for masks where the rubber needs to be thick enough to hold its shape by itself.
In the US, try Monster Makers online. Their Mask Making Liquid Latex would be equivalent to the thicker Brushable latex. https://www.monstermakers.com/rd-407-mask-making-latex/ Their Dipping Latex would be the thinner one, which is probably what I would go for to make stop motion puppets: https://www.monstermakers.com/dipping-latex/
If you are talking about casting in Foam Latex, that is a different process. I like Monster Makers foam latex or GM foam, both made in the US. (Nor sure if GM is still made, foam latex is being used less now with silicone becoming more common.) Foam Latex comes as a kit, with latex base, foaming agent, curing agent, and gelling agent. You also need scales to weigh the ingredients, a mixer and mixing bowl, and an oven to bake at 100 degrees F ( 37.7 Celsius). So it is a more complex and costly process. This is for filling the mould and baking it so you get a solid foam puppet. Here is a quick view of the process:
I was wondering about the liquid latex skin, but do you think latex is better than sillicone?
Latex and silicone are really quite different, and it is difficult to say one is better than the other without knowing the context. I like using silicone for character heads, and it makes good-looking hands too.
But latex is great for monsters, especially when you want to add some horns or give it some texture or distort it a bit. And latex can be painted more easily, glued more easily and adapted more easily.
I would caution against launching into using foam latex unless you know what you are doing. It is not a tabletop process, unlike liquid latex or silicone, and you need a decent dedicated oven and a mixer.
I prefer silicone for smooth skinned characters, because it doesn't form little wrinkles when compressed like foam latex does. For the heads of 3 child characters, silicone was the best choice. But for scale wrinkly monsters that is not a problem.
I prefer foam latex for thick heavy characters, because foam latex is much lighter in weight than silicone. That monster in the video above would be much too heavy in solid silicone, the legs would barely support it and it would not be able to bend much before springing back.
Liquid latex skin does not form the fine wrinkles, and if stuck over a urethane foam body shape the puppet is still light weight. But it can restrict the bending a bit, in a thicker character, because it will fold over well enough, but on the outside of the bend it does not want to stretch much. So it is likely to fold on the inside of the bend - like the belly - in one big fold like a rubber boot. Sculpting deep wrinkles into it will help it be more flexible - just like the corrugated rubber "boot" that covers a gear stick in a car, the folds let the rubber skin fold.
I mostly paint liquid latex on the surface of the cut foam to build up a skin, but you get better detail by casting sheets of skin in a mould. When I want that kind of detail I usually cast the whole puppet in foam latex or silicone, but Richard Svenssonto ( Bluworm ) does really nice work with bits of latex skin stuck on.
Liquid latex works well for hands, dabbing it directly over the wire armature. Fingers are thin enough, it still bends well even though it is solid. By letting the latex dry, then dabbing on little dots of latex where the knuckles go, and lines for the tendons, quite a lit of detail cn be added, and there are no seam lines to fix up like you get from casting the end in a 2 piece mould.
So it depends on the puppet, what it needs to look like, how thin or bulky it is, which material is best.