Dictionarium polygraphicum. Blue Japan.

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol I.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
1735
Take gum water, what quantity you please, and white lead a sufficient quantity, grind them well upon a porphyry. Then take ising-glass size what quantity you please, of the finest and best smalt a sufficient quantity, mix them well; to which add of your white lead before ground so much as may give it a sufficient body; mix these together to the consistence of paint.

With this mixture do over your work, and repeat this three or four times, till you see your Blue lies with a good fair body, letting it dry thoroughly between each time; if the blue be too pale, put in more smalt into the size, without any white lead.

Then rush it very smooth, and go over it again with a stronger blue; and when it is thoroughly dry, wash it twice over with the clearest ising-glass size alone; then cover it, and let it dry two days.

Then warm the piece gently before the fire, and with a clean pencil, wash your work over with the finest white varnish, repeating it seven or eight times, and then let it dry two days as before; then repeat again the second and third time, your washes seven or eight times in like manner.

Then let it stand to dry for a week, and then polish it as before directed; and lastly to give it a polish'd and gloss'd appearance clear it up with lamp black and oil.

You may make the colour either light or deep according to your fancy; if it have but a small proportion of the lead, it will be deep; but if it has a larger, it will be lighter.

Also the size for laying blues, white, or any other colour, ought not to be too strong, rather weaker, and just sufficient to bind the colours to make them stick on the work; for if it be too stiff, it will be apt to crack and fly off; and the reason of washing twice with clear size, is to keep the varnish from sinking into or tarnishing the colours.