This website was my inspiration for using borax in candlewick making. The author did a personal experiment with different wicks and found that wicks made with borax that were soaked overnight had a taller flame - which I like so it doesn't snuff itself out.
Some cotton string:
4 tbsp Borax, 2 tbsp table salt, and 1.5 cups water
Mis it all together and let sit overnight:
Dry it. Dip it in wax to coat it and let that dry.
*I used a candle warmer to melt some beeswax and then I dipped my wick in there. This saves another dish from getting ruined from the beeswax coating. East Peasy!
I was surprised how well the wicks burned. I did have tall flames and they were beautiful!