If you are using pressure to cast Alumilite you need a compressor that has an air tank, not just an air compressor that blows air, like those electric ones used around the house. Reason being, Alumilite sets pretty fast, so you need to reach pressure pretty fast. I have not attempted it but I think the alumilite would set before you reach the propper presure. I have a 4 or 5 Gal (can't remember) small pancake compresor and it works fine for casting at 80PSI in the HF pressure pot.
Eugene