You burn wood slightly to make it stronger. This was also common when making wooden spear tips. https://www.customshingles.com/blog/wood-burning-for-wood-roofs

You burn wood slightly to make it stronger. This was also common when making wooden spear tips. https://www.customshingles.com/blog/wood-burning-for-wood-roofs-shou-sugi-ban#:~:text=Yes%2C%20charring%20wood%20makes%20the,results%20will%20be%20less%20impressive https://www.customshingles.com/blog/wood-burning-for-wood-ro....