What is the best mix of water and paint for a mist coat?

Readers Digest DIY Manual says dilute paint to half strength. DK DIY Manual says dilute with 10% water. (I鈥檓 preparing to paint new plaster ceiling).What is the best mix of water and paint for a mist coat?
Are you doing this to avoid using a primer? How new is the ceiling? Plaster can be a slight pain in the butt. Most plaster should cure for 30 days before painting or use a primer designed to go onto a ';hot surface';. SealKrete works well as a barrier coat so does Sherwin Willams Loxon Primer. After that, follow the label instructions for the paint on thinning, most say no more then 10%. On a gallon that is 12.8 oz, I suggest not thinning at all, as this will lead to a thinner paint that tends to drip more and have more splatter. Not such a great idea if painting a ceiling.What is the best mix of water and paint for a mist coat?
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