I stumbled across an interesting video the other day.
Given the solution is salt based keeping outdoor guinea pigs cool using homemade PCMs seems like an good idea.
You will need food grade Sodium Sulfate, Table Salt, CMC or Xantham Gum and water to make this PCM. To store the PCM for use you will additionally need silicone sandwich bags or Large vacuum seal bags, and something to cover them like a pillow case.
Disclaimer
Using PCMs to regulate your outside guinea pigs' temperature is just a concept. I have not tried or tested it myself.
Other ways too keep your outdoor guinea pigs cool
Shade under shade is the key to beating the heat. Hay is an excellent insulator and can be used as your second layer of shade. Giving your guinea pig a cage full of Timothy Hay will allow them to burrow in it. You can also add a shallow pool for them to get their feet wet.
Thank you!
