Hi Vitali - To find the correct epoxy ratio for your mix you put the stone mix into a glass jar that you know the volume of or you do it on a scale so you know the weight of the mix. Then you add water until the volume is neatly topped up. The weight of the water is the weight of epoxy you need to add if the epoxy is close to 1000kg/m3 density. If denser then adjust the weight eg if the epoxy is 1200kg/m3 then you add 1000/1200= 830 gm of epoxy. Having a bit of air in the mix is OK depend on what you are aiming at. To get better surface finish paint on a layer of epoxy to the mould prior to adding the EG mix... Usually people add a bit less then this test defines. This is either to save some money or they are going off someone elses mix ratios.

If you use a very thin epoxy vibration is not needed... it will saturate by itself... In fact if the epoxy is very thin you can dry stack the mould and pour the epoxy in and it will flow through the mix until it tops out the mould... Give that a try small scale... Regards Peter