wrote:

I have a truck camper that is over 30 years old. Some of the plywood
in this camper is weather checked and/or rotted. It's 3/4 inch
plywood, and I don't know if it's "treated" or not.

The wood is dry.

The rotted areas are exposed to the sun sometimes.

I am soon going to sand the surface of this plywood.

What product or products would work for me to brush on this wood? I
want to stop further deterioration, and also give some strength to the
rotted areas. I'm not too concerned with the cosmetics of this plywood
after this operation, but _AM_ concerned about giving or restoring
some structural strength to it.

Replacing the plywood is NOT an option.

Then you have no option.

Once dry rot has set in, the only option is replacement.

Lew