Chinchillas learn from a very early age. If there is a mom or dad that is not real good about keeping itself clean, many times they do not keep the kit as clean as it should be kept, this "bad habit" can be passed on to the kits. It is just a habit ... but a bad one, that is easily passed on to the kits. I will not breed one that has/develops that habit.
They do not have to have the habit at first, but may even develop it after a bout of being sick or injured, or if they are allergic to the bedding being used. If one is sick or injured, keeping the cage cleaned
daily will usually help prevent this nasty little habit starting. Once it starts, it is hard to break.
The use of hardware cloth 1/4" x 1/4" or 1/2" x 1/2", is good, but even with that, the urine can continue to accumulate on the metal wires over and over, so it has to be cleaned weekly ... or you would be allowing germs, fungus, mold and who knows what else to multiply on the dirty wire.
Bumblefoot is usually caused by a small animal having to stand on wire constantly, if the wire is not cleaned regularly, it happens much faster. Bumblefoot is an irritation of the feet. They become swollen, red and can even crack open, bleed and become infected. This is very painful for a chinchilla ... just think about having your feet blistered ... that is about what bumblefoot would feel like to a chinchilla. A very severe case of athletes foot would also be a fair example to let you know what it feels like to a chinchilla.
Flat surfaces are a must for a chin to rest on at least part of the time. I have some marble tile that I use as a chin-chiller that is easily cleaned with gentle soap and water. These could be used as a place for the chin to rest ... but always keep them on the bottom floor of the cage ... you don't want them falling on the chin and hurting it. Marble does not soak-up the urine like wood does.
Drying and sanding the wood is an option ... just make sure you sand past any stained part. Do not use bleach or amonia, the fumes can cause your chin major problems. Replacing the wood selves regularly is also an option.
Good luck!
Jo Ann