###What each suit was composed of depends on which era of the Flash you are talking about. Each one had a different suit and different properties. BUT, and this is the most important part:
None of his/their suits had any particular property that protected them from destruction. The protection came from the Flash's speed-force generated aura.
The Flash's body is surrounded by what he calls his "speed force aura". This aura protects him and anyone who is running with him or carried by him, from the effects of using his speed. This includes friction and airborne particulate matter.
It also protects him from injury from high speed impacts such as punches he delivers and receives from his opponents. With this aura, he is able to absorb kinetic energy. He possesses a level of superhuman resistance to injury which at times does extend far past normal physical interactions, as received from normal combat.
###Pre-Crisis Flashes: Barry Allen and Wally West
- Barry Allen and Wally West had a ring that held their costume compressed within it. Barry invented a gas that allowed his costume to be compress and held within his ring until he needed it. It was assumed his street clothes were properly treated to take their place within the ring once he changed at superspeed.
- Barry designed a special costume. He used a special cold cast polyester he developed in college, which could be molded into miniature outfits from liquid material, that, when submersed in a special liquid, became sensitive to hydrogen, expanding on contact with the hydrogen in the air. A charge from a battery-powered ring he wore on his finger caused the fabric to release the extra hydrogen and shrink into the ring. He later revised the process, making the fabric sensitive to nitrogen instead.
###Post Crisis Flash: Wally West
- In the beginning of his career, Wally West wore a variation of Barry's costume (red and yellow) and later he changed his costume into a legacy version after Barry's death during the Crisis on Infinite Earths. Later, through master of the Speed Force, he could create his own costume out of the Speed Force energy directly. Yes, he was running around naked in a uniform composed of his psychic connection to the Speed Force. No, it didn't disappear when he was knocked unconscious.
###New-52 DCNU - Barry Allen
The new Flash appears to have taken a step backward and gone back to an armored costume he "transforms" into apparently at superspeed. This costume, like so many in the new DCNU appears as a form of armor.
