Lots of folks put cayenne pepper in the feed cause its a natural wormer. I dont know if it will keep the squirrels out tho'. They are certainly pesky once they find your feed stash. What about putting it in giant trash cans with the lock down lids? BTW...
Our local specialty bird food store used to carry the liquid spray to treat your feed. They stopped carrying it because it lost effectiveness too quickly. They suggested to check with local feed stores. (I haven't yet though).
Hot pepper will work. I put habanero in my birdseed once and the squirrels flipped out, but I didn't like risking my eyes around that stuff so I gave up. You might try other kinds of hot pepper if you like. However, I find the best deterrent to be a .22 rifle, it's cheap and effective. Anything else I have tried, the squirrels find ways around. Metal containers would work for storage, but would do nothing to stop them getting in the feed you give the birds.
