Farm silos of salt-glazed tiles are beautiful and are standing unused. I would like to recover these tiles for reuse on part of my house -- need suggestions about how to dissolve or loosen the mortar. I have found two built apparently from a kit about 1920 or so. A metal plate says The Dickey Glazed Tile Silo, W S Dickey Clay Mfg Co, Kansas City Mo USA. The tiles surfaces are about 12.5 inches horizontal and 12 inches vertical. They appear to be about 4 inches thick. The silo interior is about 14 feet in diameter. I cannot find any trace of the manufacturer now. I suspect the kit had directions for exactly the mortar mixture to use. The tiles probably have a "tongue and groove" connection horizontally. I don't know about the vertical shape. Is there a chemical that might soften mortar used about 1920? Would sand-blasting work? Is a concrete saw the only possibility? Thanks for any helpful suggestions.
Depending on your location, you might be able to use freezing weather to loosen the glazed blocks. Allow moisture to trickle over the blocks until the mortar is saturated. Do this during a sunny day when you know there will be a hard freeze through the night. If there is a lot of lime in the mortar, one or two hard freezes should do it.
If not, acid is a possibility, but an acid strong enough to eat through or soften the mortar may also be caustic enough to damage or disfigure the blocks. As well, the amount of acid required, and the effects it would have on you and the environment, make this stategy a poor one.
I suggest you try another, safer approach. First, make certain you have scaffolding around the silo, and a means of getting the blocks to the ground safely. A double block-and-tackle helps: run your rope through however many blocks you can lift safely, and tie the rope around the last block--like stringing large beads.
To start, once the roof and any other connecting hardware has been removed and lowered to the ground, use a dry-cutting blade to slit through the mortar surrounding one of the topmost blocks. With this out of the way, some light, but firm tapping with a rubber hammer should dislodge the block. You might find that once the first block is out of the way, some tapping with a rubber hammer, or a bit of light chisel work, is all that is usually required to part out the blocks.
In some of those mortar cavities, both vertical and horizontal, you will find steel rebar or pencil rod reinforcing. This can be cut with a carbide grinding disc.
Once you get the blocks free, I suggest you consider cleaning them off with detergent and steam: those blocks may be infused with the remains of all that silage fermenting within the bllock walls. It might stink things up a bit if you don't clean them off and use them on an interior application.