Balanced Alkali with Selenium toner and HCA

[tkamiya]

In an instructions for toning by Kodak literature, there is a section for mixing Selenium toner with HCA to do it in one shot. In it, it suggests adding Balanced Alkali. This component is omitted if the paper is RC but suggested if FB. It is omitted entirely if HCA and Selenium toner is NOT mixed together.

What is this for and is it necessary IF I mix HCA and Selenium toner?

I don't have it and I don't want to buy it if it isn't a critical component.

Thanks.

 

[Gerald C Koch]

The purpose of the Balanced Alkali is to insure that there is no residual acid present in the FB prints. The presence of acid can cause staining when using any selenium toner. Since there is no fiber to absorb acid in RC papers it is not needed. I have not seen any literature on mixing everything together. However, I would recommend its use since it is easy to obtain. Once a print is stained AFAIK the stain cannot be removed. Another name for this chemical is sodium metaborate and it is more alkaline than borax but less so than sodium carbonate.

 

[tkamiya]

I wonder why it only shows up in mixed-all-together instructions, not HCA, then tone instructions....