Since clay is a readily available resource in Ladakh, and perlite is not, I’ve been exploring ways to make cost effective burn tubes using local clay mixed with various other local ingredients to make stable, long lasting insulative burn tubes. Testing at the workshop has been interesting as we look for various products to mix with the clay to both give it stability, and insulating properties. So far the clay has been mixed with sawdust, ashes, chopped and dried alfalfa grass, puffed rice, barley, machine threshed barley grass (very short), hand threshed barley grass (longer) and local grass seeds growing nearby. These various clay experiments are in various stages of drying out and will be soon be ready for rocket testing… which means the tubes will be placed into a rocket burn situation to see how they hold up. We are looking for both durability and insulation, which is easy to measure. If the inside of the tube is over 800C and the outside is still cool to touch, then its insulating well.