How to seal waterblock barbs using teflon tape

From TPU Reference

When you replace the barbs of a waterblock it is likely that there will be a bit of water leaking out. One way to fix this is by using an O-Ring, rubber works best in my opinion. But I prefer to use Teflon tape since it's easy to come by and pretty cheap.

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Doing it

Cut a generous piece off. I use about 15 cm for a 1/2" barb. This is just a rough guideline. Depending on how lose your threading is you may need more. It does not matter if the edges are cut nicely.

It is very important to make sure that the Teflon tape does not unwrap when you are screwing in the barb. Start with the tape going from left to right for a barb which screws in in clockwise direction. Press the start of the tape firmly to the barb so that the tape sinks into the threading and makes good contact. If it does not want to stick, wet the barb/tape a little bit.

Now carefully wrap the tape around the barb until you have two layers on top of each other.

Now stretch the tape by pulling on it while you wrap it around until you are completely done. Make sure that it fits snugly. When you are wrapping longer distances overlap about half the tape width each turn.

When done right you can barely make out the individual layers on top of each other. I marked the end of the tape in the picture. If yours isn't as clean, don't worry, Teflon is very forgiving as long as there is enough to fill the gaps.

Before you install the barb, check if some Teflon tape is blocking the flow. If it does you can easily push it away with your fingernails.

There should be good resistance when screwing in the barb with your fingers. If you can barely move it with your fingers use a wrench. Using a wrench it should be fairly easy now.