Aluminium Foundry

Step 5 Refractory

At this stage the foundry is almost ready for the refractory stage. I used a plastic can of paint with a bit of extra cardboard on top to form the inner furnace core leaving 2" space around for the refractory. For the lid I used some cardboard pipe from an empty gravy box to form the oulet lid hole. The refractory I used is ready made fire cement it comes in a big 25kg bag, all that is needed is to add a bit of water. I started mixing it using a very small amount of water until I got sticky paste. Too much water is bad for any refractory. On the internet many home made refractorys are combined of Perlite (cruashed)+cement+silica sand and fireclay. Good refractory means good insulation, good insulation keeps the needed high temperature in the furnace. I started filling the furnace from the base ramming the refractory all the time with a timber block to get all the air bubbles out, then I placed the plastic core into position and filled it all the way up with refractory keeping 2" width and after that filled the lid.

Comments

[Omnombulist]

Wonderful ible! I just finished making a similar furnace and will be adding a hinge after seeing how nicely yours worked. I used regular portland cement and cured it for 18 days before firing. It is pretty thoroughly covered in hairline cracks after 4 firings and the outside gets terribly hot. I am guessing I will have to recast the cement before too long and am interested in fire cement.
How well Is your refractory holding up? How many times have you fired it?

[cendit]

I can´t see if the refractory partially blocks the air inlet. I'm asking in case that is some kind nozzle, because the area reduction. Thanks