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When applying glue (be it wood glue, plastic glue, or superglue) from a metal tube, I very often find that the glue keeps oozing out of the nozzle even when I'm no longer squeezing the tube, even if held upright. Sometimes, I can stop it by gently pressing the sides of the tube to make it more circular in cross-section, increasing its inner volume. However, that is not always possible, nor does it always help.

What is causing this behaviour, and how can I stop it, or prevent it starting in the first place?

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    Sometimes it is due to an increase in temperature... – Solar Mike Jul 9 '19 at 10:49
  • Thinking about when this happens - is it usually when the glue is in a metal tube? This can also happen with a caulking gun as well. – JPhi1618 Jul 9 '19 at 14:33
  • @JPhi1618 Yes, it happens with (thin sheet) metal tubes which you press/squeeze by hand to get the glue out (kind of like toothpaste) - like this. I have yet to use a caulking gun, so I can't comment there. BTW, English isn't my native language and I've never really needed DIY-related vocabulary, so sorry if I sound weird. – Angew is no longer proud of SO Jul 9 '19 at 15:07
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When you squeeze a tube or bottle you are increasing the pressure on the inside of the container, and the material inside the tube is forced out. For thicker materials like glue or sealant, it takes some time and more pressure to make its way out of the tube.

For plastic bottles and tubes, when you release pressure with your hand, the container springs back to something close to the original shape and there is no more pressure in the tube. However, with a metal tube (or similar, rigid material), the tube will attempt to keep its new shape. The metal will continue to apply pressure to the material in the tube and the material will drip or ooze out.

The common solution is to only squeeze a small portion of the tube, and realize that the product will not come out immediately. Squeeze a little, then wait. However, even when you are careful, you might get more product than you wanted and trying to squeeze the sides of the tube to make the shape more of a cylinder is a good technique.

The easiest way to "squeeze a small portion" is to squeeze from the bottom. When you squeeze the middle, you are deforming the entire side of the tube. When you squeeze a little at the bottom and flatten the tube as you go the pressure you apply is very localized.

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  • If the pressure was « localised » then why does it come out the far end? – Solar Mike Jul 9 '19 at 17:37
  • @SolarMike, what I mean is that you are only compressing a small area of the tube. Starting at the flat end, you can squeeze a small area and only crease and deform the metal in that area. If you squeeze the center, much more metal and shape change is involved. Any pressure created only has one place to go, and thats out the front. – JPhi1618 Jul 9 '19 at 20:01

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