Need to know what the labs are using as far as investment for PFM's. We are getting to tight of fit. Looking for an investment that is stable and that will fit. We use ringless, fastfire investment, and up to 4 wax patterns per ring (90gram rings). Please inform me what investment you use, How many wax patterns you use in a 90gram ring , fast burn out or slow? And what is a good noble metal and investment? Thanx for your help.