Recently I mixed some yellow ink with white ink to create my own warm off-white color and used it to undershade red. Looks pretty similar to your accidental undershade. Was very happy with the result. Ps I only needed 1 drop of yellow to 40 drops of white. The yellow (Yellow Orange Azo from Liquitex P83) is quite strong. The drops of white might have been smaller, but still.
Recently I mixed some yellow ink with white ink to create my own warm off-white color and used it to undershade red. Looks pretty similar to your accidental undershade. Was very happy with the result.
Ps I only needed 1 drop of yellow to 40 drops of white. The yellow (Yellow Orange Azo from Liquitex P83) is quite strong. The drops of white might have been smaller, but still.
Great for abaddon or horus's face