Generally interior wood requires no special wood protection against moulds and blue stain. Except in wet areas, where wood takes on a moisture content of more than 20%.
Inside there it is sufficient to coat the wood with a transparent water dilutable wood stain. An ideal product for this is the Brillux Lacryl Woodstain 235. For the first coat on new or bare wood, you can diluted the woodstain with 10% water and then it can be primed.
After that it is recommended to sand the wood with a P120 grit sandpaper and afterwards you can apply the final coat e.g. Brillux Lacryl Woodstain 235.
After this final coat the result will be a smooth and protected from moisture natural wood surface.