Colourless, odourless, 100% pure medical grade paraffin.
All oil based mediums have an odour when fired, some also when applied. Paraffin is non volatile so the only odour present is when burning it off during firing. The smoke and the smell is the same as that you get when you burn classic candles, which are also made of paraffin. Room ventilation helps carry this smell away.
Liquid paraffin is also the main ingredient used in baby oil, chosen for this purpose due to it being odourless, tasteless, dermatologically tested and approved, not allergenic, and free of preservatives or antioxidants due to there being no risk of rancidity.