A $20 dry box

Camera lenses are expensive, yet do not devalue with use, unlike camera bodies, so it makes sense to keep them well. For this purpose, I built my own dry box, since they're surprisingly expensive on eBay, and hard to find in stores.

For the box, I used a Sistema Klip It food container. I like these, since they secure very well and they don't use flimsy "living" hinges, those hinges made of plastic that bend. I got this when Coles was selling them at half price - $5

To dry, I went for silica gel off eBay. This seems more expensive than I remember. I used to get a bottle for $5 from camera shops. I got 2 × 200g for about $15. This is a bit overkill. Another website says 200g will protect about 400l. That's the size of my fridge. The silica gel comes in porous bags, which look like those that come with food. This probably means that those that come with food are reusable too. An important issue is how to regenerate the silica gel. Since I don't have an oven, I bought from someone who says they can be regenerated by microwave. Actually, if one person says they can, they all probably can, no matter who's selling them. Another important issue is the blue silica gel contains cobalt chloride, used as an indicator as to when it should be recharged. Cobalt chloride is arguably dangerous, so if you're going to be regenerating the silica gel in your kitchen, you don't want cobalt chloride. The new orange-green indicator used is supposed to be safer. The silica gel I bought looks like it has some blue beads mixed into it.

Lastly, I got a hygrometer. You can skip this step if you trust your set-up, but I like to measure things. I got this in China, but you can buy one off eBay for about $3.

This is the final set-up. When I put the bag in, it weighed 260g and the humidity in the box was 70%. In 1 hour, it dropped to less than 30%! Actually, weighing silica gel is a better way to measure its capacity than using indicators.