Ive had great success making all sorts of soaps with pretty colours and fragrances, but my biggest problem is getting a bar to last. The nasty ones I can buy in a shop all seem to last 4-5 weeks but mine only last maybe 2. I have reduced superfat to about 5% but that often results in a bar with a white residue - presumably the lye. I can harden it with beeswax, but harder doesn't seem to correlate with longer lasting. Any tips please??