Wood Ash

Experiments with hardwood ash taken from our fireplace.

Lye

Combining wood ash and water produces lye. It is easily separated by pouring off the water and then driving off the water with heat. Needs to be done in a stainless steel pot. Clean up with vinegar. Keep vinegar on had because the lye is a caustic alkali.

Cerement

The ash that remained after removing the lye was used to test making cement.

The first block was a mixture of sand and ash, not very precisely mixed. The resulting block was not very strong.

Several 2" square blocks were cast from pure ash. After about 2 weeks they were fairly hard. When placed in water they don't seem to disolve, though they do seem to soften a little and the water turns brownish suggesting there was some lye left in the ash.

Some of these blocks were fired. These blocks were noticeably lighter, though that may just be from driving the remainder of the water off, or it could be a chemical reaction. These blocks dissolved rapidly in water. I believe the substance left behind is basically lime. This should be suitable to use as a mortar.