Rinse cyanotype with alkaline tap water ?

[mug]

Hello,
I a starter with Cyanotype. I just bought the chemicals for ‘New Cyanotype’ .
Now I’am reading the siderotypemanual chapter ‘Notes on the New Cyanotype Process’.
I have an quenstion about washing with tap water.
In my home town in The North of The Netherlands the tapwater is between 7,6 and 8,0.
So only very limited Alkaline
Mike Ware wrote:
Water Wash: immerse in gently running water for ca. 30 minutes.
Alkaline water (pH >7) must not be used
Is is necessary to make neutral tap for rinse ?
How to do ? Take an bucket tap water and add a small amount of hydrochloric acid ?
Should I use pH meter of test strip to make the water, say pH 6.8 ?

 

[Tetium]

Hello,

I had the same problem with alkaline tap water at home (near PH 8).

When I developed my first cyanotypes in these alkaline water with no treatment,
my cyanotypes were too pale (more bluish, than the expected strong blue).

So I slightly adjust my tap water with citric acid and that changed a lot !
No more pale blue, but a great deep blue as I expected.

In order to do that;

1. Fill your tray with the right amount of tap water you normally use to rince,
2. then add citric acid in the tray by 1 ml at the time (a bottle of 50% diluted citric acid in pure water is a good thing to have),
3. stir and test the PH of your water and repeat (by adding 1 ml of citric acid) until you reach the right acidity (I develop with a PH ~6.5)
4. Note the amount of diluted citric acid needed for your tray and voilà !

 

[sly]

I use vinegar to bring down the pH of my water.

 

[mug]

Thanks.
I’am going for the citric acid. Just bought today 1 kg by local drug store. Not expensive less then €10,-.
I was also today in a store were they sell 5L hydrochloric acid 30%. Even touch the outside of the closed (thin) plastic container gives my the some acid on my hands. Small bottle of 0,5L 10% HCl are better to handel.
Citric acid is much easier to handel versus hydrochloric acid.
I just oder on ebay Test Indicator paper PH 5.4-7.0 for a bit more then €1 (for 80 pieces)
Because I have not an pH meter at home.

 

[pdeeh]

Different acids seemto change the image colour in my experience.
Note also that citric acid is more efficient at washing out the unwanted iron compounds than other common acids

 

[Andrew O'Neill]

I use citric acid or vinegar.