Never use chinchilla dust, it will make your gerbils sick. Or at least, that's what you have probably been told. The internet has instilled a deep fear of chinchilla dust and even sand, causing groups and forums to encourage the use of playsand or reptile sand. Often they go on about silica (sand) being bad for gerbils. Well, did you know that chinchilla dust is actually made of pumice stone, a type of volcanic rock.
Dust is an irritant to the sinuses and nose. Inhaling fine particles everyday may damage the lungs. Its for this reason that I strongly recommend you do not keep dust or sand in your gerbils cage. Gerbils are not from the desert, they do not live in the Gobi Desert of anywhere with sand dunes. This is another common misconception. Gerbils are actually from the steppes and plateaus of Mongolia, which are a type of arid grassland.
First, we should ask “Why do gerbils take sand bathes?”
Gerbils use sand bathes as part of regulating their body temperature. Gerbils have a harderian gland behind their eye that excretes porphyrin which looks like red tears but is waxy. Gerbils mix the polyphrin and their saliva and spread it on themselves. Depending on temperature they may use more or less of each to spread on their coats.
In cooler temperatures they spread more porphyrin into their coat. This helps them retain heat. In warmer temperatures they mix more saliva in to increase evaporation cooling. Gerbils can not sweat so they smear saliva on themselves. Truly hot gerbils may actually urinate and spread that on themselves too.
Dust baths help gerbils remove the porphyrin from their coats. Porphyrin is waxy and insulates the gerbils from heat loss through evaporation. Finer dust or sand particles are better at wicking away liquids, oils and waxes from the fur. Generally speaking chinchilla dust is made with finer grades of pumice. Below are two pictures of chinchilla dust. I dropped a droplet of oil into the dust and then shook the plate. The dust quickly wicked up the oil and formed a little ball, which could easily be picked out. Sands not designed for bathing are not very good at soaking up oils, and may not be good at removing porphyrin and other oils from your gerbils coat.
Some owners enjoy providing sand for their gerbils to play in. Coarser sands like reptisand, calcisand, and play sand are often used for this. The sands are coarse, and may be too coarse to roll in. Some sands like play sand may be abrasive to the coat. Gerbils still enjoy digging in these sands, just know that due to their large size they will not wick or absorb oils from the coat. However, they tend to contain lower amounts of dust. These types of sands can be offered daily, but I still would not recommend keeping sand sand or dust inside your gerbils cage. A separate play area is preferred. If your gerbils fur looks a little rough or oily and their fur isn't laying smooth, the gerbils may need a real sand bath using a chinchilla dust or sand that is meant for bathing. They should be given about 5-15 minutes to roll around and clean themselves, and then remove the sand bath. Gerbils shouldn't need a sand bath much more than once or twice a week, and they'll appreciate it more during the summer than the winter.
Here’s some pictures of a young schimmel female, MS Incredulous, rolling around in a dust bath.