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Hi everyone,

I'd like to ask a question regarding a problem I've been having while
carbon coating.  I am using a Denton Desk V coater with turbomolecular
pump and rods consisting of compressed powdered graphite (from Ted Pella,
1/8” diameter, grade 1 “spec-pure”).  I can obtain coats of appropriate
thickness (i.e., between 1st-order red and 2nd-order blue) that look very
good.  However, after coating polished brass or glass, when I place a drop
of methanol on the surface of the coat, the coat disintegrates within a
matter of seconds.  Has anybody seen this sort of behavior before?  I
assume that it must be due to presence of contamination under the coat. 
I've checked the inlet to the roughing pump, and I see no oil residue
after several months of use.  Any suggestions?

Brian


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Brian Joy
Electron Microprobe and ESEM Lab
Queen's Facility for Isotope Research
Department of Geological Sciences and Geological Engineering
Queen's University
36 Union Street
Kingston, Ontario K7L 3N6

cell phone: 530-220-0434
lab phone: 613-533-2595
fax: 613-533-6592

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