Fill the bucket 1/4 full with water. If you are using an acrylic additive that some products require, add that now.
Start to add small quantities of the thin set. Mix with the mixing blade between additions.
Add thin set to your mixture until it resembles peanut butter. Let it rest for five minutes. Water content, humidity and heat will all play a factor in the quantity of the thin set you will need to add. Rely on the feel of the thin set rather than prescribed ratios.
Use the mixing blades to stir the mixture for another five minutes. Then, it is ready for application.