I am using 0.5% Allantoin to formulate a O/W Emulsion. In the beginning stages I used glycerin to dissolve the allantoin and then added the mixture to the cool down phase of my mixture but then I read that 1,3 propanediol is a better solvent to dissolve it. My question is how long should I leave the allantoin to dissolve in the 1,3 propanediol ? I left mine to dissolve for about 6 hours and I could still see some undissolved bits. By the way, I am dissolving 0.5% allantoin in 2.5% 1,3 propanediol. Grateful for some guidance.