High-density polyethylene (HDPE) is used for milk cartons, fuel tanks and pipes. Previously, HDPE could only be welded together by melting the surface of the HDPE. However, recent innovations have created epoxy-based glues that allow HDPE to be attached to other polymers such as PVC, fiberglass and steel. Different brands of HDPE glue, like Pro-poly and TAP Poly-Weld, will have different manufacturer's instructions. However, what they do have is common is a need to prepare the surface of the HDPE to accept the glue.

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Prepare the surface of the HDPE before gluing.

Sanding HDPE

Step 1

Use 120-grit sandpaper to rough of the surface of the HDPE. If you are combining two pieces of HDPE, sand both surfaces.

Step 2

Use a shop-vac with a bristle attachment to remove the HDPE dust. Any dust will prevent the epoxy from adhering to the HDPE.

Step 3

Mix the glue according to the manufacturer's instructions. Epoxy glues must be mixed with a hardening agent to form a secure bond. Some epoxy glues have an ejection gun that mixes as it dispenses, while others will need to be mixed by hand.

Step 4

Apply the glue thickly to the surface of the HDPE.

Step 5

Press the glued HDPE to the surface with which you wish to combine it.

Step 6

Clamp the two pieces together until the glue has cured. The time required will vary by manufacturer.

Melting HDPE

Step 1

Light a propane torch and adjust the flame until it is yellow at the tip. Yellow flame is cooler than blue flame. The object is to melt the surface of the HDPE lightly. A red or blue flame will scorch the surface.

Step 2

Pass the flame back and forth over the surface of the HDPE where you will apply the glue. Continue for 2 or 3 seconds. If you are working with a round piece, you will need to turn the piece as you apply the flame to heat it evenly.

Step 3

Test the HDPE by placing a drop of water on the surface. If the surface has been sufficiently breached, the water will spread out. If there are patches that have not been melted, the water will bead, and you will need to repeat the flame treatment.

Step 4

Prepare the epoxy according to the manufacturer's directions.

Step 5

Apply the glue thickly to the surface of the HDPE.

Step 6

Press the glued HDPE to the surface with which you wish to combine it.

Step 7

Clamp the two pieces together until the glue has cured. The time required will vary by manufacturer.