Opalanie Natryskowe : An emulsifier is a thickening agent and is one of the most common ingredients in tanning cosmetics. It makes oil and water mixtures more stable. Two examples of cheap emulsifiers are propylene glycol and borax. Propylene glycol has been linked to health problems and is a known skin irritant. Wearers laying out in the sun with a lotion that contains propylene glycol may develop breathing problems due to the substance turning to gas at high temperatures. Borax is another cheap emulsifier often listed by its scientific name, sodium borate. It too has been known to cause skin irritation and has even been banned for use in cosmetics in some countries. When investigating the ingredients in a lotion, look for laureth-7.