Spot clearing blues to white / bleaching cyanotypes

[tgeis]

I am trying to find a way to spot bleach out certain areas of blue, after the exposure/washing process. I have tried household bleach but it leaves the white yellowish. I am looking for a clear white. Any pointers are much appreciated! Thanks

 

[Derrel]

Would "Farmer's Reducer" work? Is there a modern, current substitute for that product? APUG might have some knowledgeable people, as might some type of alternative process guru.

 

[compur]

From the instructions for Photographer's Formulary Cyanotype chemistry:

"After Treatment: A spot application of a 5% solution of oxalic acid (5
grams per 100 ml) can be used to clear the whites of blue. Wash the print
after its use. A Prussian blue water color can be used for spotting the
areas."