08:47 – Arrrrghhh! Leakage is the bane of anyone who ships liquids. I was making up the bags of hazardous chemicals for the biology kits the other day. There are seven of those. I’d distributed 30 sets of the first six to plastic bags. When I was about to add the seventh, Sudan III stain, I immediately noticed that the bag that contained 60 filled, sealed, and labeled 15 mL dropper bottles of Sudan III stain had liquid in the bag that had leaked from one or more of the sealed bottles. Ruh-roh.
The problem is that that stain is made up with a 50/50 mixture of 70% isopropanol and acetone. Both have low viscosity, and both are difficult to keep in a sealed bottle. The combination of the two was apparently too much for the dropper bottle cap, and several of the bottles had leaked. Dropper bottles are inherently more leak-prone than bottles with standard screw caps, so I immediately filled, capped, and taped a bottle of Sudan III stain using a standard PP cap with a PE liner. That bottle is standing on its cap right now. I’ll give it several days to leak. If it lasts until next week with no leaks, I’ll assume that that cap is good enough to prevent leaks during storage and shipping.
In fact, I’m seriously considering abandoning the use of dropper bottles entirely and shifting to using standard screw caps exclusively in all of our kits.