Bleaching the reclaimed wood

Hi there,
I have attached a door made up of reclaimed wood. Inner part is made by joining 2 planks. Dark line in between the 2 plank is due to years of exposure to atmosphere (sun,rain and humidity), kindly suggest a better bleaching medium for this type (dark shade) of worn out wood. I dont find any difficulty with wood which are 1 inch above.

Regards.
Grandis

You could try deck cleaner (oxalic acid). Probably the best thing.

https://www.bunnings.com.au/cabot-s-...clean_p1521451

It's a bit hit and miss, so try it somewhere hidden first if possible.