Applying Plastic Sealant to Bond Plastic and Metal

JB Weld Clearweld
  • 1-3 hours
  • Beginner
  • 25-50
What You'll Need
Plastic sealant
Grinder (optional)

Plastic sealant serves as a protective layer for most household and industrial materials. Although sealants are similar to adhesives, this viscous material has higher flexibility and elongation compared to adhesives. This makes sealants more advantageous compared to adhesives when used in items that requires exposure to the elements.

Plastic sealants come usually in tubes and could be applied directly to the surface. But depending on its purpose, it would be best to follow the right procedure to obtain better results.

Step 1 - Know Your Plastic Sealant

Some sealants are designed for household use, while others for industrial. In most cases, most household sealants require minimal procedure when it comes to applying the sealant to plastic and metal.

If you plan to use this on an industrial level, you have to take note that depending on the items needed to be bond, you have to check the strength and flexibility of the sealant. You can always consult your local hardware in any case you need help when purchasing the right plastic sealant.

Step 2 - Prepare the Metal

Before applying the sealant, you need to prepare the metal first. What you need to do is to get a handheld grinder and smooth the mating flanges. Make sure to remove any substances on its surfaces.

Step 3 - Prepare the Plastic

You can use soap and water to clean the plastic. Just make sure that after washing, that the plastic is thoroughly dry before applying the sealant.

After cleaning the plastic, get sandpaper and smooth the bonding areas of the plastic. As soon as you’re done with the plastic and the metal, then you’re set to bond the two together.

Step 4 - Prepare the Sealant

caulk seeping out of a caulking gun

Most industrial sealants come with a dispensing gun. Follow what is written at the back of the packaging if the item requires you to do additional preparation before applying the sealant. In most cases, you need first to insert the sealant packaging into the dispensing gun in order to let release the sealant out.

Once you’ve done that, squeeze a small amount of sealant just to level the plungers and to make sure that the adhesive comes out properly from the dispenser.

Step 5 - Apply the Sealant

After preparing the sealant, the next thing you need to do is to tilt the dispensing gun to apply the sealant onto the plastic. Use clamps or rivets to hold both metal and plastic together. This method makes the process less messy. As soon as you are done, allow the sealant to stand for at least one hour, unless otherwise directed, before releasing the clamps.

Step 6 – Clean the Surface

Sand or grind to smooth the surface. Just to be sure, do this after two to four hours to make sure both metal and plastic are intact. Remove the mixing tip to avoid cross contamination when storing the sealant.