How much thinset do you mix?
Similarly one may ask, can I mix half bag of thinset?
Mixing thinset isn't rocket science and doesn't have to be mixed to exact proportions. If you eyeball a portion of a bag and it's too thin - add a little more thinset, if it's too stiff - add a little water.
Herein, how do you mix thin sets?
Mix your thinset mortar and water until it has the consistency of a thick peanut butter. Don't be afraid to add more water or mortar to get it right. The consistency is very important. You know you have it right if the mortar on your trowel doesn't drip off but can be shaken off.
In addition to producing an uneven surface, applying too much thinset can create costly cleanup headaches and add unnecessary time to a project. Simple installation rules eliminate the possibility of this potential problem.