#24 While using oil in a lock would work, the oil will collect crud and dry out over time. The proper thing to use for locks is graphite lubricant. Arbitrary example from Amazon: https://www.amazon.com/Panef-Corp-Powdered-Graphite-Lubricant/dp/B0016GZQ60
"Sure, you can use the button to replace a missing one and you can use the piece of fabric to patch up a hole. But they're actually there so you can test how the fabric reacts to different detergents."
#24 While using oil in a lock would work, the oil will collect crud and dry out over time. The proper thing to use for locks is graphite lubricant. Arbitrary example from Amazon: https://www.amazon.com/Panef-Corp-Powdered-Graphite-Lubricant/dp/B0016GZQ60
https://www.amazon.com/Panef-Corp-Powdered-Graphite-Lubricant/dp/B0016GZQ60
Now I don't use hairpins but I would think the side WITHOUT the sharp pointed end would be better against your scalp?