In a recent post, Coldamus refers to repairing broken plastic mouldings by 'aluminium and epoxy'.
I have another method which I use for repairing broken plastic mouldings.
Usually the moulding material is a complex blend of plastic types to give the right balance of temperature stability, strength, flexibility, hardness. The method used by Coldamus depends on achieving a good bond between the plastic and the epoxy. The aluminium is to give rigidity to the repaired section to avoid further breakage of the mend at the join line.
My method uses Loctite 406 and cotton wool.
Loctite is an isocyanate instant glue. It generally does not bond well to smooth surfaces. However, isocyanate reacts violently with modern cotton wool, producing a high temperature reaction.
The first step is to lightly glue the broken parts together to allow strength for the final glueing. The cotton wool (caulking cotton, cotton wool from cotton buds etc) is then placed in close proximity to the break line and then doused with loctite 406. After some 10 30 seconds, the reaction proceeds and turns the cotton wool into a hard solid mass. The hardness of the reacted cotton wool reinforces the break line.
I used this method many times to re-glue broken plastic screw thread bosses on radio/TV/CD player cases. I used it to re-glue the screw bosses to a Holden Commodore front seat escutcheon. I used it to repair the centre console on the TP Magna.
I use the method universally for broken plastic moulded parts and haven't suffered any failures.
Loctite cross links by moisture exposure and it needs to be kept in a refrigerator.
Hope this is useful info.

Well, I'll be . . . . good tip!

So any other brand Super Glue work as well??
I have some that is Cyanoacrylate Adhesive?? Vee

isocyanate

Isocyanates are what 2 pack paint has in it once the hardener is added so be carefull of the gas given off!!! Vee

http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documents/514/Isocyanates.pdf

What a great tip,thanks. As these cars get older and the plastics get a little brittle a good repair option is great to know. Cheers!

Tried it with the $2 shop super glue and ended up with a nice hard wad of cotton wool fused to the plastic coat hanger i had handy!! Vee

I use loctite 406 cos it works well. I have used other 'botles' of isoc but I wasnt convinced of the state of the isoc. i keep the loctite in the fridge; it lasts better.
The warning about the fumes is REAL. Very pungent. BUT, you know you have a result when your nose hurts!
pr.

I love 406. Great for gluing the rubber door seals off 2nd Gens too. I stored mine in the freezer, lasts a long time....

I love 406. Great for gluing the rubber door seals off 2nd Gens too. I stored mine in the freezer, lasts a long time....

I recently welded a couple of tabs back onto an interior panel (RH seat belt cover panel) using a 30W soldering iron. Got the idea off U-Tube although I found the idea of using an electrical tie for filler no good. Extra plastic is needed to add to that being welded not unlike welding metal. The best filler plastic is that from an identical scrap panel.

The soldering iron needs to be good & hot & you need to keep the soldering iron tip on the join so both surfaces become liquid. It's a tricky job needing a steady hand. Both sides need to be welded so not recommended where the join is clearly visible. Scrap plastic needs to be added to fill the gap & strengthen the join. Fine metal wire can be introduced to reinforce the joint further.

It's vitally important the the item to be welded/joined is properly positioned & braced.

The cotton wool (caulking cotton, cotton wool from cotton buds etc) is then placed in close proximity to the break line and then doused with loctite 406. After some 10 30 seconds, the reaction proceeds and turns the cotton wool into a hard solid mass.
I didnt understand this step. Do you rub the bud over the join at some point?

rumpfy was last logged on..-05-2014 . he should see this post pop up

from what I read .
.you have to work fast ...the cotton and loctite become the workable mass you use to restore and reinforce the break line cracks and gaps
..
very fummy take care

Hi KWAWD.
The cotton bud has a cotton material that reacts with the loctite. I dunno what the cotton bud material is, but you need to wind the cotton wool around the joint and then douse with loctite. The heat of the reaction will bond the cotton wool on to the plastic parts.
Instead of a cotton bud, you can use normal cotton wool; the sort of things used to wipe disinfectant on to a wound. Just tease out the cotton wool material and wind it round the joint. It does fume badly and you wont want to breathe the fumes in.
Hope this helps.

Hi KWAWD.
The cotton bud has a cotton material that reacts with the loctite. I dunno what the cotton bud material is, but you need to wind the cotton wool around the joint and then douse with loctite. The heat of the reaction will bond the cotton wool on to the plastic parts.

Thanks, that explains it really well. We need a vid of this, if anyone is doing it please consider a vid!

I recently welded a couple of tabs back onto an interior panel (RH seat belt cover panel) using a 30W soldering iron. Got the idea off U-Tube although I found the idea of using an electrical tie for filler no good. Extra plastic is needed to add to that being welded not unlike welding metal. The best filler plastic is that from an identical scrap panel.

The soldering iron needs to be good & hot & you need to keep the soldering iron tip on the join so both surfaces become liquid. It's a tricky job needing a steady hand. Both sides need to be welded so not recommended where the join is clearly visible. Scrap plastic needs to be added to fill the gap & strengthen the join. Fine metal wire can be introduced to reinforce the joint further.

It's vitally important the the item to be welded/joined is properly positioned & braced.

This is a good idea using a soldering iron, as you mentioned you need to use the same type of plastic, also good for repairing the little tabs on bumpers

I've used the soldering iron method a bit on my Magna plastic parts,seems to work very well. The loctite and cotton will trick sounds good too....plastics are weird stuff,what works on one type may not work on another. Good to have a few different methods and see what works best on the specific part.