How do you guys clean your plastic helmets / hard hats? dishwasher - no heat?
Most hard hats / helmets today are made of high density polyethylene (same stuff used in milk jugs) or polycarbonate ('Lexan'). The shell can usually be wiped clean with normal (hand) dishwashing soap, Simple Green, 409, etc. Rinse and dry. Some companies also sell disinfecting wipes or solutions if the PPE is shared (separate topic). I would not use a dishwasher.
The suspension is usually made out of a combination of smooth plastics, fabric, and absorbent foam, which is harder to clean. I would remove the suspension and hand wash using gentle laundry detergent, then rinse well, and dry. Ironically, the suspension is often thought to be the 'more important' part of the protective helmet, and is recommended to be replaced more frequently than the helmet shell itself. It can also be more expensive to buy. Some safety supply companies sell OEM sweat band components or aftermarket liners to replace the foam headbands, which get the grungiest (IMO) and are the hardest to clean effectively.
Hardhats have an expiration date when just exposed to UV rays never mind industrial cleaners. It is something like 5 years. Before I would clean it, I would just chuck it out and get a new one.
@Philbert can you comment on life expectancy of helmets?
Hard hats usually have some type of date code embossed or stamped in them. 'Rule of thumb' is to replace after 5 years of
service. So if the helmet was made in 2012, and stored in that famous 'cool, dark place', but just issued last week, don't throw it out. If it was made in 2016 and you leave it in the rear window of your truck in Alabama, take a close look at it: look for cracks, deep gouges, a dull appearance, etc. Damage to the suspension may not be visible - replace after any severe blow / impact. Basic helmets can often be found at hardware, home, and farm stores for as little as $6 to $12.
http://s7d9.scene7.com/is/content/minesafetyappliances/Helmet Care and Use FAQ - EN
http://www.oshatraining.com/osha-hard-hat-questions-blog.php
Philbert