You gotta use some of that cooking oil spray right onto your forehead breh
Your problem is you've got too much friction between the wave cap and your forehead which is causing uncomfortable chafing/irritation. A few others have been playing around with vaseline, graphite, and various other substances in order to alleviate these kind of problems but the KEY is to get it taken care of early so your forehead doesn't end up looking like Troy McClure. I would recommend you go down to your local hardware store and experiment with a few of the solvents or lubricants that they stock and see what works for you, maybe bring your wave cap along and check each substance and it's friction modifiers. I have some literature that I can send you if you require any further assistance