I was wanting to keep gym equipment in my car but in winter it gets to below freezing and in summer it can get to 120+ in the car. Will soap or shampoo left in those conditions undergo any denaturing that damages their ability to clean? I know they freeze in cold weather but have no idea if after they warm up there is any lasting damage.
the components could separate and you would need to remix.
You can buy “bar shampoo” which is like a bar of soap. I’m sure that would stand up fine to freezing.
Cold shouldn’t be a problem at all. Liquid shampoo might separate with freeze -thaw cycles but it should mix back together. Heat won’t break down the detergents but maybe some scents or other minor components will degrade over time.
I work with frozen or boiling detergent solutions all the time in lab, including with SDS which is commonly uses in shampoo.
I left a bottle of shampoo in our deer cabin last year. The cabin was winterized with no power, and spent weeks below freezing. When I returned to open the cabin in the spring the shampoo was unchanged (as far as I could tell, I used it the next morning).
It was the cheap stuff, if it matters. (Suave)