This is not true. Beads can most definitely turn your units a yellowish tint. None of our other beads are doing this at all. This is not the "contaminated oven" bright greenish color... this looks like A1ish, almost. If the beads are wrong... or even not meant for sintering... then they can most certainly contaminate the units. This is why I asked what beads he was using as there are several types. Grinding... silicate... It seems the rep misguided me. For the record, these beads are not bright white... they are off white.
Drops are not always necessary either if you sprue and place your bridges in the oven properly.
We rarely use drops and never have issues with warpage. Plus they are a pain to remove