I'm looking for a viscous fluid which will evaporate (completely) rather quickly.

If propylene glycol evaporated like acetone, that would be the dream ticket, but neither the viscosity nor the volatilty need be quite that high.

Non-toxic would be a plus!

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    $\begingroup$ It may be possible to exploit variation of viscosity with temperature, depending on what you're planning on doing. For example, isopropanol is relatively volatile but non-viscous at ambient temperature. However, at -78 °C it becomes very syrupy. $\endgroup$ – Nicolau Saker Neto Oct 6 '18 at 23:46
  • $\begingroup$ 2-propanol is the closest I've found (boiling point 82.6, viscosity 2.038 at room temperature). Not terribly viscous, but possibly viscous enough. $\endgroup$ – barneypitt Oct 7 '18 at 8:30
  • $\begingroup$ Application: want to apply a paste made from metal powder and a suspending medium to a surface which can be mildly heated (50-60C). Heating should leave the powder only, evenly distributed, with no residue of suspending medium. $\endgroup$ – barneypitt Oct 7 '18 at 8:34
  • $\begingroup$ Which metal is it? Some solvents may not be compatible. Can you place the surface in a vacuum chamber? That would open up more options. Have you looked into commercial metallic pastes and their compositions? This may be a partially solved problem. For example, silver paste is fairly viscous and often uses terpineol. Also, a sufficiently high weight percentage dispersion of the metal in any liquid will likely make it quite viscous, but it's a matter of knowing whether such a suspension will be stable, which will also depend on e.g. particle size. $\endgroup$ – Nicolau Saker Neto Oct 7 '18 at 9:32
  • $\begingroup$ Moderators: How does putting this on hold help anyone? The question is exactly as specific as it was intended to be, not an iota more, not an iota less. There's nothing I can change. $\endgroup$ – barneypitt Oct 7 '18 at 22:19

Volatility and viscosity are 2 properties going each against the other.

A volatile liquid has rather small molecules a/o rather weak intermolecular bonds.

A viscous liquid has rather big molecules a/o rather strong ( often multiple ) intermolecular bonds.

A partial solution to the task is to have composite liquid, a volatile liquid mixed with either viscous liquid ( e.g glycerine), either with dissolved thickener ( like polyvinylalcohol or vaseline/wax )

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  • $\begingroup$ Wouldn't the volatile liquid just evaporate first, leaving the viscous liquid? $\endgroup$ – barneypitt Oct 7 '18 at 8:26
  • $\begingroup$ It would. But what else would you expect ? $\endgroup$ – Poutnik Oct 7 '18 at 8:28
  • $\begingroup$ As stated, the liquid needs to evaporate fully - no residue - which I imagine rules out using a dissolved thickener. $\endgroup$ – barneypitt Oct 7 '18 at 8:36
  • $\begingroup$ That is why I have written partial. $\endgroup$ – Poutnik Oct 7 '18 at 8:37
  • $\begingroup$ Full solution may not exist, It is hard to have something small and big, strong and weak at the same time. Viscosity means strong bonding. Volatility means weak bonding. $\endgroup$ – Poutnik Oct 7 '18 at 8:39

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