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I have this UV-reactive invisible ink (a clear liquid.) According to the data sheet, it is suspended in an isopropyl alcohol base. Unfortunately, this is terrible for my particular application for two reasons: (1) it dries too fast (I need it to stay wet on a rubber stamp for ~15 minutes before stamping.) (2) It is too "thin" and thus bleeds into the porous material a little too much.

I've used regular black ink refills that (I believe) are water-based and they are perfect (except for the visible, non-UV-reactive part.)

If I understand this stuff correctly, the UV ink would be UV-reactive particles suspended in isopropyl alcohol base. If I were to mix this with water to get a workable liquid, I would likely dilute the ink too much.

Is there a way to transfer the suspended particles from the isopropyl-alcohol to water? Perhaps by mixing them, letting them separate and then let the alcohol evaporate off the top?

Alternatively, to reduce dilution I've considered finding a clear viscous liquid (think simple syrup without the stickiness) or even a clear gel as a thickening agent. Unfortunately, I don't know of a good viscous liquid or gel that would evaporate without a visible/sticky residue. Possibly one of the inactive ingredients in a hand sanitizer gel?

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    $\begingroup$ I suspect that suspended is the wrong term. To chemists suspended means that solid particles are "floating" in the liquid. I'd rather suspect that the compound was dissolved in the isopropanol. $\endgroup$ – MaxW Jan 30 at 23:05
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    $\begingroup$ isopropyl alcohol is miscible with water, so a mixture of water and isopropyl alcohol won't separate, which is what I think you're suggesting. however, if the ink is soluble in water or a water/alcohol mix, you might be able to evaporate off a good bit of the alcohol and restore the volume by adding water. On a separate point, glycerol and propanediol (1,2 or 1,3) are used as thickeners in hand sanitizers, but they would all leave a residue on paper. $\endgroup$ – Andrew Jan 31 at 1:04
  • $\begingroup$ After asking this question, I researched the ingredients in hand sanitizer gel and recognized glycerin as a possibility. I tried a series of tests, mixing with water, mixing with hand sanitizer gel and mixing with glycerin (vegetable glycerin, according to the package) and all tests failed miserably except for the glycerin, which worked admirably well. $\endgroup$ – pauln Jan 31 at 17:16
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Slowly drive off the alcohol in a vacuum or by gentle heating. Replace the lost alcohol with distilled water. Experiment with small volumes first to ensure that heat does not degrade the ink.

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