Here you can buy this H2O2 in pharmacy without prescription and usually is used during restoration of old furniture.
There is also a usage of 1:10 ratio with water to disinfect the whole tree, about the dry wood it should give a more natural gray color to the wood, I will try some small spot.
I’ve never heard of H2O2 in woodworking, but you learn something new every day, how is it used?
I think you’re confusing Zerotol(35% strength H2O2) and 3% H2O2 from the store. The adage of “too much of a good thing” here applies. The concentration of 35% is still watered down when we use it as a root wash for anti-fungal treatment, and is quite corrosive and dangerous in its undiluted form, so handle with care. Rubber, non-reactive gloves, and a mask and protective clothing is a must, even while making your dilution. Ever put store bought peroxide on a cut and watched the oxygen bubbles form? Now imagine if 35% peroxide touches your skin!!!!
Store bought 3% H2O2 is already weak enough to handle and can be used, again as a watered down, light antifungal treatment, and it will also help with some types of bugs.
H2O2 is an oxygenater regardless the strength, if you have root rot in a tree, an application, at the right dosage can kill off the bacteria/fungus causing the rot, and provide oxygen to the soil and roots.
I’ve never seen/herd/ or used it myself for deadwood.
That being said, like sulfur can be diluted with water to very light concentrations and reapplied in an additive manner until the desired effect is achieved. Take a standard dilution of lime sulfur, cut it in half, or do even a 25% mix of an already diluted-from-the bottle application, and you will get a weaker response that won’t be that stark white I think your trying to avoid, and if it’s not enough, let it dry and reapply