Loose stuff can be wiped off with clean cloth - like a cotton flanelette or a microfiber- or vacuumed, as long as you have a HEPA so the mold doesn't get sprayed around your work space through the exhaust. A light going over with grated art gum eraser will remove the rest of the loose stuff.
As long as RH is below 75-60% you shouldn't have a problem with it re-activating. Thymol is bad for your health and yellows things. An alternative is ethanol. You can buy it at chemical supply or, in smaller quantities, at the liquor store. In my twisted brain I keep thinking they call it "Golden Glow" which I know is wrong, but it is 100% alcohol, and some people use it to make fancy liquors.
If it were safe for the object you could brush it on, but better method (safer) is to put a dish of it in a makeshift polyethylene tent which also covers the artwork and/or mat, so the vapors and alone have contact with it.
In 99 44/100 cases out of 100, this ethanol fuming isn't necessary. If you live in a very humid climate it might be worth it, but remember mold spores are everywhere and if it is damp enough to reactivate old mold it is damp enough to start a new unrelated colony.
Rebecca
