I had my first time tonight, not sure I did right .

The o2 absorbers are a plastic material, how does it absorb O2 thru the plastic?

I had read the geat warm out in the air, but the didn't even seem a little warm after a couple laying on the table for 30 minutes.

*** I checked some of my Mylar bags and they look like vacuum packed coffee bags.  I sealed them about 80% pressed out all the air I could and dropped the o2 absorbers in and finished the seal. So it looks like they are working.

If you had them in the open air and they were not even a little warm after 30 minutes they are probably not any good.  I have received bad ones in the past.  Another way to check is to squeeze them in your hand.  If the inside is lose granules then should be ok. If the inside feels like one solid mass fused together then probably no good.  Hope this helps.

See OP.