Polyurethane Repair - Firebird Ground Effect

Here, we have a 1979 Firebird front ground effect that has a four-inch crack and a broken tab. These older Firebird parts are made of polyurethane plastic. So for this repair, we will be using Polyvance’s airless plastic welder and urethane welding rod.

Other repair products, such as two-part adhesives, don’t adhere to polyurethane plastic very well. However, when using urethane welding rod as an adhesive, you can get a strong, permanent repair.

In this video, we will show you how to repair small cracks and tabs in polyurethane parts using Polyvance’s Model 7 airless plastic welder and R01 urethane welding rod.

You can use our Mini-Weld Model 7 or the integrated airless welder that is part of our nitrogen plastic welding systems to perform the repair. These two options are recommended because you need to be able to control the temperature of the welder.

This article can help you determine if your plastic part is thermoset polyurethane or a thermoplastic.

Always wear proper safety gear while working!

Let us know your thoughts on this video by leaving a comment on YouTube!
Click here: https://www.youtube.com/watch?v=UKIILcmWF0g

Products Used:

Note: This is a list of the Polyvance products that can be used to make this repair. This list does not include sanders, grinders, or other common tools you will need. If you have any questions, please don't hesitate to call technical support at 800-633-3047.

• 1000 Super Prep Plastic Cleaner (several options available) OR 1001-4 EcoPrep Plastic Cleaner
• Aluminum Body Tape (several options available)
• 6122 Heavy Duty Round Burr
• 6125 Tapered Burr
• 2000 Flex Filler (several options available)
• Waterborne Primer Surfacer (several options available). We used 3043 All Seasons Black Jack
• Polyurethane Welding Rod and an Airless Plastic Welder(choose a method below):
• Polyurethane Welding Rod with the airless plastic welding side of a nitrogen plastic welder. Our current nitrogen plastic welders include the 6027HT Standard Welding Tip.
• 5700HT Mini-Weld Model 7 (A 230V kit is also available). The 5700HT kit includes a 15 foot starter roll of polyurethane welding rod and the 6027HT Standard Welding Tip.
• Note: Make sure you are using either the 6027HT Standard Welding Tip or the 6029 Bigfoot Welding Tip when using the round polyurethane welding rods.

Video Notes:

• This type of repair can be done with the Mini-Weld Model 7 or the airless side of a nitrogen plastic welder.
• English Closed Captions have been provided for this video. Click on the CC button to turn them on or off.
• The length of this video is in no way representative of the actual time required to perform a complete repair and therefore should not be used for estimating purposes.

Music Credits:

• "Super Friendly" Kevin MacLeod (incompetech.com)
  Licensed under Creative Commons: By Attribution 3.0 License
  http://creativecommons.org/licenses/by/3.0/
• "Wallpaper" Kevin MacLeod (incompetech.com)
  Licensed under Creative Commons: By Attribution 3.0 License
  http://creativecommons.org/licenses/by/3.0/

English Transcript:

Here, we have a 1979 Firebird front ground effect that has a four-inch crack and a broken tab. These older Firebird parts are made of polyurethane plastic. So for this repair, we will be using Polyvance's airless plastic welder and urethane welding rod.

Other repair products, such as two-part adhesives, don't adhere to polyurethane plastic very well. However, when using urethane welding rod as an adhesive, you can get a strong, permanent repair.

In this video, we will show you how to repair small cracks and tabs in polyurethane parts using Polyvance's Model 7 airless plastic welder and R01 urethane welding rod.

As with any repair, you want to start out by thoroughly cleaning the part to remove any dirt or grime. Next, align the crack and use aluminum tape to hold the crack together. On the back side, v-groove about halfway deep into the plastic, making sure the v-groove is centered along the crack. If the crack extends to the edge of the part, make sure to v-groove along the edge, about two inches on each side of the crack. This edge v-groove provides extra reinforcement for the repair. If repairing a tab, v-groove about an inch around the crack.

To weld polyurethane plastic, you will need to set your airless plastic welder to the PUR setting. Begin welding by feeding the rod through the tip of the airless welder, holding the tip slightly above the surface to avoid burning the base material. Move slowly so that the v-groove is completely filled with welding rod before moving on. Finish the weld by doing the edge v-groove last. Weld a broken tab the same way; move the welder slowly to fill the v-groove completely. Smooth out the welds if necessary.

After the plastic is completely cooled down to room temperature, remove the aluminum tape from the front side. Use plastic cleaner to remove any adhesive residue left behind from the tape. Next, make a deep v-groove halfway into the plastic, making sure to expose your existing weld on the back side. There is no need to make an edge v-groove on the front. After v-grooving, weld the front side.

Remember to hold the welder tip slightly above the surface, making sure not to burn the base material. Once the welds are complete, allow the plastic to cool to room temperature.

Once the plastic is cool, grind the front welds using 36 grit to 50 grit on a Roloc disc. Next, sand the repair area using 80 grit sandpaper. Sand at least four to six inches around the welds. Here, we are refinishing the whole part, so we sanded the paint completely off. If repairing a tab, now is the time to drill the tab hole out.

Blow the part off with air and use plastic cleaner to remove any dust. Next, apply filler to cover the welds and any other imperfections. Here, we're using Polyvance's 2000-T Flex Filler 2 epoxy. Once the filler has cured, sand and block with 80 grit sandpaper and finish out with 180 grit sandpaper.

Now the part is ready for primer. Here, we used Polyvance's 3043 All Seasons Black Jack waterborne primer. You may need to block and prime multiple times to achieve desired appearance.

Polyurethane parts are often thought of as unrepairable. However, these parts can be repaired and restored to like-new condition by using products and techniques from Polyvance.

Thanks for watching! Let us know in the comments what you thought of this repair, and check out our other videos for more plastic repair tutorials.