I'm having trouble finding the source of contamination on glass. FTIR showes silicone rubber along with other spikes. One possibility is that some cleaning agents used on our gloves are causing it. I'd like to know if either isopropyl alcohol or triethylene chloride could attack the polymer of some rubber gloves ("natural rubber" says the manufacturer, I suspect a blend with nitrile and/or silicone) and cause it to break down. I've searched Google, however no helpful links result.
Silicone is a notorious contaminant. Nearly all silicones contain cyclic penta- and hexa-dimethylsiloxanes (called cyclic D5 and cyclic D6, in the business), as well as higher cyclic siloxanes. These undergo a ring-opening polymerization reaction, which puts down a very thin contaminant layer which is almost impossible to remove. The disk drive industry hates silicones, because these contaminant layers play havoc with the head-disk interface. Note that certain cosmetics such as lipstick and solid stick antiperspirants contain cyclic siloxanes as major ingrediants. That's a problem because production line workers may be using them.
Silicone may infiltrate a production process through a variety of ways. In the disk drive industry, it has been learned through cruel experience that the syringes used to dispense adhesives (for example to attach the disk head to the actuator arm) can contain troublesome amounts of silicone originating in the silicone-based mold release agents used to make the syringes. Even when non-silicone mold release agents are specified for your syringes, there can be cross-contamination through the air from silicone mold release agents used on neighboring production lines in the same facility. Insidious, indeed.
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