Thinset cement is basically a combination of three additives. Portland cement is used in thinset to provide the bonding mechanism; sand is added to temper the cement; and a liquid latex mortar additive is added to give the thinset pliability, allowing the materials to expand and contract without cracking. You can make your own thinset by purchasing these items separately and combining them. This process will allow you to make more thinset for less money.
Sift the brick sand through a 1/4-inch wire screen to remove any rocks or debris from the contents. Rocks and debris will affect the thinset mixture, causing it to be lumpy. Place the sifted sand on a clean plastic tarp or poly plastic.
Add 1 gallon of clean water to a 5 gallon bucket. Add two scoops of sifted sand to the water using an old coffee can. Mix the sand with the water using paint mixing stick or meter stick. Add more water--1 gallon at a time--if the sand is not soupy after mixing it with the water.
Add two coffee cans full of dry Portland cement to the sand and water. Mix the contents using a heavy duty drill and paint mixing bit. Purchase the bit at any hardware store and rent or purchase the drill from any tool rental store. Combine the ingredients so that you have a pancake batter consistency. Add more water to soften the mixture and more sand and dry powder to thicken it.
Allow the blended mix to set for 15 minutes out of direct sunlight. The Portland cement will harden quickly. Therefore it is important to keep it away from the sun to preserve the mixture.
Add 2 cups of liquid latex to the mixture and blend the contents using a drill and mixing bit. Allow the contents to set for 5 minutes and remix using the drill and mixing bit.
Test the pliability of the thinset by placing a small amount the size of a dime in direct sunlight. After 5 minutes, squeeze the thinset between your thumb and forefinger. If the dried mixture is not pliable, then add 1 cup of latex to the mixture and blend again.