What he’s doing is a common “laundry home remedy,” but it isn’t actually something that works in a modern washing machine.
Aspirin (acetylsalicylic acid) is mainly used as a pain reliever, but in water it breaks down into salicylic acid. Because of that, some old household tips claim it can help with things like:
- whitening clothes
- removing sweat stains
- “refreshing” laundry
In reality, in a washing machine it doesn’t do anything useful. The concentration is too low, the wash chemistry (detergents, enzymes, water temperature) overwhelms it, and there’s no solid evidence it improves cleaning. At best, it’s harmless but pointless; at worst, it’s just extra residue going through the machine for no benefit.
Why your father-in-law insists on it likely isn’t chemical—it’s habit and memory. People often attach specific “methods” to routines they shared with a partner, especially after a loss. So the aspirin may be more about continuing something his wife used to do than about cleaning performance.
If you want a practical way to handle it without creating conflict, you could:
- quietly stop adding it and see if he notices (he may not), or
- gently suggest an “updated” version of her routine that keeps the spirit but uses modern detergent instead.
If you want, I can also suggest what actually helps with stains or whitening depending on the clothes he’s trying to wash.
