How to interpret this recipe for Lynn's Glossy Gray-blue green

[martha peddicord]

I am trying to mix the recipe that is the glaze on Barbara Hanselman's  'Egyptian Bowl'.

Gerstly borate     50

Silica                   30

EPK                     15

Titanium Dioxide   5

Also Add  for gray

Soda Ash     2.50

copper carb  2.00

RIO              1.00

Cobalt carb  0.75  

Then it says, FOR BLUE  , add

Copper carb  2.00

Does this mean, that for the blue, that I add all the ingredients for gray, and then also add the additional 2% copper carb? 

I have mixed it with just the copper carb added and it does not come out  anything like the picture.

A potter I know is using it successfully and it is taupe-pink in the bucket, but he won't share how he mixed it.  That leads me to believe the RIO must be in there.

[Wyndham Dennison]

I would say the 2% copper is without the other color ingredients. Best to do some test tiles with these and other colorants.

The soda ash looks like it keeps the glaze to the alkaline side where copper goes blue instead of green.

If the glaze has 2% copper and adding 2% more, that's getting rather high but might be ok, just use test tiles to see what you get.

Wyndham