William Bronson wrote: I'm building out of Perlite and Rapid Set Cement All.
I wet the Perlite,let it drain,then I mix the two ingredients at 1 part Rapid Set to 6 parts Perlite.
I stack square wooden forms around a round metal duct,mixing and packing as I go.
I have not fired these cores yet, but they do set up hard.
The Rapid Set Cement All is available at Home Depot at about $20.00 american for 50lbs.
I chose it because it is a Calcium Sulfoaluminate cement , with at least one msds document listing the decomposition tempature at 2460°,which is a little low for use in a rocket core,but time will tell,and you can't beat the price.
I am interested in how this recipe has worked for you. Do you have any pics or comments on longevity?
paul wheaton wrote:Perlite starts melting at around 1400. We have lots of perlite glass blobs from risers that had perlite.