thinset is very fine grade aggregate combined with concrete, which is essentially a very smooth creamy mortar mix. It often has latex or acrylic polymers added to strengthen it and create better stickiness and bond. So yes thinset and mortar are both cementious adhesives.

Unfortunately, marketers have applied the name thinset to other premixed products and confused matters as they cannot be cement based and NOT cure in their containers, those are often mastic type adhesives that are plant based glues and will not hold up the way concrete will.

Good explanation of what thinset is. I was confused for years about "thinset" and "mortar." I even asked at Lowes one time and couldn't get a straight answer. I got my answers on this board, from nicethyme and slowmedown.

As I understand it, thinset and mortar are the same thing. You can mix up small amounts at a time and use it as an adhesive. You can also spread a thick amount of it and press tess into it. You can also grout with it. The reason for using thinset is that it holds up outdoors.

You cannot use it as a sealer (in the sense of applying it and wiping it back off as you would a clear liquid sealer). Perhaps the confusion came about because someone described using it as grout.

I would recommend staying away from any premixed thinset, mortar, or grout.

The previous posters are essentially correct. Mortar is merely a broader classification. Thinset is really a shorthand way of saying thinset mortar, and is one of several types of mortars you can buy. You can also get medium-set mortar if you are laying large heavy tiles or mortar designed for laying bricks or concrete blocks.

You can use thinset in either of the ways you describe, spread it onto the surface, and press the tess into it, or put the thinset onto the tess and press them onto the surface. Both methods can work, its mostly a matter of which makes job easiest. You can even do both, spread the thinset in a thin even layer onto the surface, and butter the back of the tess, and press then into place. When people refer to using thinset as a sealer, they mean coating the surface with a thin layer of thinset and let it harder completely, so that the surface is sealed, before starting to attach tess to it.

They are also right that if it is pre-mixed, and comes in a bucket, it is not thinset, period, irrespective of any label on the container.

Very clear and concise Bob, Thanks

Thanks. THese answers really help. I've bought some thinset from Home Depot and I'm hoping to experiment with it this week!