Thread: Welding or fibreglassing plastic

Very tricky to weld this stuff, as the older material dries out with age. Even with newer material, burn-through can occur, and over-build doesn't seem to help much. Probably best to get a vinyl liner from a pond/pool shop and install within your pond.

Joe

Hi Buzza
the best stuff to weld polyethylene with is the same stuff. zip ties and ice cream container lids arent always compatible.If the pond has a lip that you can cut a strip off that should work.the plastic welding gun I use is a converted heat gun with the nozzle reduced to 8mm ( needs to have variable heat settings) and added a feeder tube for the welding rod.(I paddle plastic canoes over sharp rocks )
cheers underfoot

Thanks a lot Joe and Underfoot. I have an old heat gun laying around somewhere and I don't want to give up on it just yet. It is a great pond.

I have fixed a number of kids toys with a soldering iron on low and hot melt glue.
Got to get right through the thickness though. No good just doing a bit on the surface.

Good luck.

My husband had a plastic wine fermenter welded in Adelaide - will get the details for you when he gets home.

Sorry. I forgot to mention he won't be home for a fortnight. On the phone all he could tell me was, "Some German name, in Adelaide." Boy, that really helps, huh.

Originally Posted by Shedgirl

Sorry. I forgot to mention he won't be home for a fortnight. On the phone all he could tell me was, "Some German name, in Adelaide." Boy, that really helps, huh.

Menzel Plastics perhaps?

Menzel Plastics could well be the people to help. I can't thank you all enough for your suggestions and help. The pond itself is a Heissner. It may have to go to a crash repair place.

Buzza,

Silicone won't bond to PE properly and it will thus always leak under pressure but the black PE can definitely be welded. Underfoots solution is the best. After you weld the crack you can also weld a patch over the top of the crack, and another patch on the other side. I have also welded white to black PE with long term (20 year) success, the important thing is that they are about the same "molecular weight", in practice this means about the same hardness.

A crude patch weld can be done as follows.
Cut a patch the size of what you need to cover the area with an overlap of at least a cm.
Clean the strip and area around the crack with detergent to remove any oil and lots of water to remove the detergent.
Place a couple of strips of wood alongside the crack and lay the patch on top of the strips
Using a hot air gun, play the hot air back an forth onto the strip and the crack to a point where they go soft, droop a bit and even start to glisten - in practice this means more heat on the crack than the strip
Watch out you do not burn the PE otherwise you are screwed.
The degree of softness for white PE is that it starts to go clear and slightly gooey.
using wooden or metal tongs place the hot soft strip over onto the crack and use a piece of wood to firmly push the strip onto the surface around crack. Weight it down while it cools
Do the same on the back side of the crack
You should practice this before having a go on your real crack.
I have fixed many containers this way.

Sourcing no-cost suitable PE for patches is tricky. Some food/drink containers (eg some translucent plastic milk containers) are PE but these are usually low molecular weight PE. Black PE retic pipe (the thick stuff you can thread) is too thick to get flat but can be sliced up to make excellent welding rods.

I hope some of this helps.