How to mix latex into mortar for tile?

[GeekBoy]

How much of this white latex additive should I mix into this dry mortar mix in order to set my porcelin tile? It doesn't have directions on the bottle, it just says it can be used to increase mortar flex and bond strength for setting tile... but it doesn't tell me how much water to replace with this stuff?! That is what I'm doing, right...? Replacing water in favor of latex liquid? Help! Thanks!

[Richard J Kinch]

1 part to between 0 and 4 parts water is a typical recommendation, but it depends on how much your stuff is already watered down. If it looks the consistency of whole milk, about 1:2 would be a good guess, or 1:4 if you're cheap.

Here's great technical sheet on a typical product: