I recently got a laser that is water cooled via a couple of clear plastic tubes (about .5 cm diameter). I have heard it can happen that algae or other undesirable inhabitants can get into such tubes and cause problems. I have also heard that wrapping the tubes in something dark to keep light out can help with this issue. However, I have not heard of a good material for wrapping the tubes with, and I am looking for suggestions.

Ideally I would like to be able to slide a sheath of some opaque material over the tubes. Something like heat shrink (unshrunk) might work. I have also seen braided nylon sheaths for covering cables, but they don't look very opaque. What's the best option?


2 Answers 2


I use polypropylene glycol in my CO2 laser tube under florescent lights and have not had any problems. It also comes with the added benefits of freeze protection and corrosion protection.

If you would still like to block out the light you can use black hdpe tubing for plumbing and helical wrap the tube with blue masking tape. You could also spray paint the tube with black spray paint and remove it with acetone in the future if necessary. The most maintainable would be to put it inside an enclosure; which would have the added benefits of structurally protecting it and keeping users safe from high voltage.


I work at a laser manufacturer, and we ship all of our water-cooled lasers with a polypropylene glycol/water mixture, and we recommend that it be replaced on a yearly basis. The coolant tubes are translucent so the fluid is exposed to room lights.

  • $\begingroup$ What ratio do you use? $\endgroup$
    – James
    Jan 16, 2019 at 21:31

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