I use only soy in my candles and love working with it. However, I use pillar wax for my tarts. It is an all natural blend of palm and coconut wax from MC candle supply. It is just firmer and works better for the tarts without losing the all natural angle. The all soy is a little to soft and doesn't always want to pop out of the clamshells. I have tried lots of different soy waxes and I ONLY use MC's golden soy blend I just love how creamy it turns out and it has a great scent throw. It's like others have posted though, trial and error are usually your best bet.:rolleyes2