Hans

I can supply a little chapter and verse on comparisons between MPK and
MEK (figs below in order MPK and MEK

NFPA Health index 2, 1 (whatever that means!)
BP 102, 79.6 °C
TCC FP 7, -9 °C
Vapour density 3, 2.5
Vapour pressure 4.72, 12.71 kPa at 25°C
Heat of vaporisation 9.18, 8.25 cal/g at 25°C
Water solubility 43, 223 g/kg
TLV OSHA (PEL) 200, 200 ppm
TLV NIOSH 150, 200 ppm
STEL OSHA 250, 300 ppm
Oral LD50 1600, 2737 mg/kg

I interpret this as MPK being marginally more toxic than MEK and
somewhat less prone to cause chilling during evaporation, hence slightly
less risk to cause blushing.

Xylene is decidedly more toxic (PEL 100 ppm) but may be marginally
better than MPK for chilling during evaporation, although there would
not be much in it. Toluene would be slightly worse on both counts.

Brian

Kathy Kuhlow wrote:
>
> What causes white residues after conformal coating?  The coating is an acrylic and after the first coat there appears to be a white residue and after the 24 hour cure the coating appears very dull and still has some of the white residues.  The residues almost look like water flux residue but it isn't.  The supplier that the coating was purchased from says it is strictly humidity related and only a cosmetic issue.  There is no visible loss of adhesion.  The solder mask is a LPI matte finish.  Can this be part of the problem?
>
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>
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