Plastic Welding a Crack on Urethane Plastic
There are many different types of plastic. This repair is on Urethane.
Urethane is a yellow plastic that is relatively easy to work with, either by welding or bonding.
I chose to weld this crack and bond afterwards for extra strength.
The first photo shows the crack on the inside. The holes had been put in it so to wire tie it so that the crack would not get any larger.
I initially was going to bond this only, this was cleaned up better than this after this picture once welding was decided upon.
First you want to V out the crack with a die grinder, or some similar fashion and remove all paint from the area to be repaired.
Second photo is of the crack on the outside.
This area had been repaired previously by the bonding only method, but the damage was considerably less at that time.
Sliding on the side of the hood on a iced over gravel road will do this!
The Urethane Supply Company welder that I use.
The urethane welding rod.
I tape the item in place on the back side.
I also use a plastic cleaner to clean the plastic before doing any welding or bonding.
Picking the correct welding rod is crucial. The wrong rod, and it does not weld properly.
Then I proceeded to weld up the crack and use the iron to smooth it out some.
For extra measure I also ran a second bead over this crack.
The finished weld. If you did not want to do a cosmetic repair, you could stop here.
Here Dominion Plastic Surgery is used as bonding and cosmetic repair material.
Here Dominion Plastic Surgery is used on the inside to further strengthen this repair.
Plastic mesh was also applied in the wet bonding material to enhance the strength of this repair.
Here the repair is sanded, and ready for primer.
Note that not a lot of the repair material was needed since the crack was held in place properly.
A flexed Urethane grade primer has been applied.
I allow plenty of flash time before coats, and medium light coats is all that is necessary to obtain a nice finish.
When sanded, it will be ready to paint.