The older experiment delt with a Wood-Ceramic composite surface. Super strong coating for wood without changing the appearance. No acid bath for this process.
Popular Science, October 1992. Advanced Ceramic Labs at the University of Washington in Seattle (USA).
Researchers have also made wood-ceramic composites that are 20–120% harder than regular wood, but still look like wood. Surprisingly simple, the process involves soaking wood in a solution containing silicon and aluminium compounds. The solution fills the pores in the wood, which is then oven-cured at 44°C (112°F). According to the lab’s research director, Daniel Dobbs, such experiments have impregnated the wood to depths of about 5 millimetres (0.2 inches). Furthermore, deeper penetration under pressure and curing at higher temperature have yielded a rock-hard wood-ceramic composite that has approached petrified wood.