The underarms of my husband’s shirts get a waxy like build-up over time. I guess it is a mixture of sweat and deodorant. (He will not change his deodorant.) I have tried spraying with white vinegar, bicarb soda, tea tree oil, soaking. Can you suggest any way of treating shirts from new to prevent this happening. Thank you.
217200cookie-checkshirt underarm stain
You mean this?
https://www.bunnings.com.au/kenco-5l-heavy-duty-auto-degreaser_p6101169
White vinegar, bicarb soda, tea tree oil all sound like Shannon Lush solutions. Get some Kenco from Bunnings and use it as a prewash. Let me know how it goes