Generating bubbles / foam is mostly reconstitution technique, but if they’re stable, not clearing up within 30 minutes, it’s a sign of poor formulation (excipient ingredients, ie “filler”) and/or the presence of damaged (unfolded aka denatured) rHGH.
The rHGH monomers (individual functional molecules) present in the bubble “walls” unfolds and oxidizes. This is a well known, proven in many experiments, path of rHGH degradation. It’s why commercial rHGH often contains a surfactant ingredient. To prevent this from happening. The most common is Poloxamer 188. UGLs know this type of degradation doesn’t show up in the tests we use, so they don’t bother. (Just like dimer was high until it started being tested, and they started making sure to minimize it).
Also, using less than 1ml per 15iu can make this problem worse.