In a process of biodiesel product from waste cooking oil I am first pre treating the oil with methanesulfonic acid and methane to reduce the FFA content. Then, I separate the acid layer before treating the oil layer with sodium methoxide and methanol. Could someone explain why if I use a signifcant amount of methanol I get two layers - one brown and one black (glycerin) but if I decrease the amount of methanol I get a fluffy white solid which takes time to settle. Is this still glycerol?