I know there are some previous posts about desicccant packs (silica gel packs) and about recharging them. Several suggest putting them in the oven for a couple of hours at around 200 degrees. My question is for clarification. Does this work for any desiccant pack that contains silica gel, like the packs that come in shoe boxes or some food products? Or can only certain kinds of desiccant packs be so "recharged". Because if it's the case that any pack will work, I've already got lots of silica gel packs just waiting to protect my camera gear! Thanks.