Dear all concerned after carrying out thorough analysis of these Greiner Gel tubes.I have determined the following.Recommended Greiner centrifuges speeds are represented in G force or RCF of 1800g.The RPM will therefore certainly change from one centrifuge to another depending on blade size.Most problems associated with poor gel seperation or gel disintergration are caused by incorrect centrifugation or recentrifugation.Plasma Gel Seperation speeds are 2200g's or RCF all for 10 minutes.Before jumping to analyser problems/probe coating,try centrifuging your Greiner tubes at the recommended speeds.Swing out buckets are required avoid fixed rotor heads.My Greiner tubes spin down fine and I've followed all the supplier recommendations.