Bookkeeper spray was mentioned on several preservation and conservation sites but was quite expensive especially once shipping was added. After the previous spray hadn't worked I was hesitant at parting with more money particularly was postage was almost as much as the product but with no guarantee of success.
There is a fair amount of technical information on the subject but a lot of it refers to mass deacidification of whole books or libraries or that you need a degree in chemistry to access.
I did find a few useful articles on basic paper treatments on the Book Arts Web and a ton of information to be found http://cool.conservation-us.org including here.
I had a eureka moment to discover this, a site that explains how to treat the acid in paper using milk of magnesia tables and soda water. It seemed a bit Heath Robinson but after reading the science behind it I figured it was definitely worth a try.
Excited, I headed to Boots to buy my Milk of Magnesia only to discover that it has been discontinued. Another dead end. Undeterred I looked for the active ingredients and found could buy them on Ebay but couldn't find the specific quantities and combination needed. I compared Milk of magnesia to other similar remedies and found that Rennies were pretty close...
I threw caution to the wind and sacrificed a couple of pages from an acidy old paperback.
As per instructions I used one Rennie tablet crushed and added to one litre of soda water. The bottle was inverted gentle several times and then left to stand in the fridge. As I understand it the magnesium carbonate and calcium carbonate dissolves into the carbonated water. The water is carefully poured into a shallow dish leaving the chalky sediment in the bottle. I soaked the pages for about 20 minutes then patted them dry before pressing between sheets of blotting paper. The water was surprisingly discoloured and the paper slightly cleaner.
When completely dry the page was not as flat or smooth as before treatment but it was acid neutral when tested with the pH pen. I don't think I would risk it with a special book pages but for my purposes I think it was worth it.