Repairing plastic

[Kittyhawk]

I need to repair some cracks and stiffen up areas on an ABS plastic sink splash back.
First option is general purpose epoxy resin. Internet opinion is equally divided into 'epoxy works great/useless - didn't stick at all'. Possibly negative opinions are based on a lack of correct preparation.
Second option is from the American company JB Weld. They have a specialised epoxy called PlasticWeld which is said to adhere extremely well to ABS. At the price they want for it, so it should.
Third option - ABS plastic dissolves in acetone. Apparently people make up a thick slurry by dissolving pieces of ABS in acetone. This is said to take about 18 - 24 hours. When ready it is applied to the work piece. The acetone in the slurry reacts with the work and the whole thing cures to a homogeneous mass, almost like welding. I like the sound of this but am a bit worried by the workpiece being only 1mm thick and it dissolving away to nothing before the acetone has evaporated out.
Has anyone had any success with repairing ABS with any of the above methods please?

 

[Bingy man]

I’ve no knowledge of your preferred methods as never had much success with plastics. I have however had some success with those metal staples that you melt into the plastic from behind . I loaned one of a friend but don’t recall the make . Also not sure what type of plastic I was repairing but it did work so it may work in your case..

 

[Tris]

Last time I did a similar repair, on a caravan vanity unit, I laminated another piece of abs on the back using plumbers pipe solvent. Worked well and is still strong. Have also heat welded cracks on a front panel with a soldering iron and filler stick, wasn't pretty though.

Tried the acetone method, didn't work for me at all, couldn't get the consistency right

 

[Yojevol]

I've tried JB PlasticWeld and was distinctly unimpressed. It doesn't 'weld' plastic and it didn't adhere well to the plastic I was using. However JB also make Plastic Bonder which adheres to anything. I've used it for several plastic to metal joints. It has a problem though. The twin dispenser is a pita. If I were buying again I would separate them. There are cheaper versions available that come in a pair of conventional tubes.
You could also consider epoxy putty which is touted for plastic pipe repairs although I've never tried it.
Brian

 

[ps.harris80]

Have a look on YouTube, there are loads of videos showing different methods of fixing cracks in plastic, although most use heat to melt plastic (cable ties seem to be a popular source of plastic in these) and strengtheners like staples or even fine wire wool also melted into the repair.

I have used JB Weld plastic before and it did work well but is a very strong mix and may melt or distort thin plastic. JB Weld original is one of the strongest epoxy's available and might well be enough for what you want, but it does that about 12 hours to start to cure and 24 hours to set rock hard.

 

[sneggysteve]

I use Milliput for turning - may be suitable here?

https://www.milliput.com/

 

[Kittyhawk]

Last time I did a similar repair, on a caravan vanity unit, I laminated another piece of abs on the back using plumbers pipe solvent. Worked well and is still strong. Have also heat welded cracks on a front panel with a soldering iron and filler stick, wasn't pretty though.

Tried the acetone method, didn't work for me at all, couldn't get the consistency right

Hadn't considered pipe solvent - I have some and will try gluing a couple of bits of ABS together and torture it to death and see how it goes. Same job as you did - motorhome vanity unit. Good suggestion. Thank you.

 

[Kittyhawk]

However JB also make Plastic Bonder which adheres to anything.

I bought a twin tube ofJB Plastic Bonder a while back which I believe is a filler type consistency when mixed. The plan for the repair was to glue some sort of doubler on the back of the hole and then fill and fair with the plastic Bonder. It sounds like a doubler of ABS glued on a la Tris's method using pipe solvent and then filled with JB bonder is the way forward. Quite enthused about trying it tomorrow. Thanks your advice.

 

[Superduner]

Depending on the configuration of the repair you might find a way to use a line of bicarbonate of soda with superglue dribbled onto it. I've found that to stick well to most plastics. Look on line and you can find black powder that also works and blends in with the black plastic.
It heats up while reacting (which it does really fast) and sets hard. The repair can be sanded down.

 

[GuitardoctorW7]

I use Acetone and ABS shavings to make a slurry for binding repairs on guitars. if you scrape the shavings into a bottle and add acetone you'll get a slurry in about 1/2 an hour. I also use the baking soda and super glue trick. Water thin CA works best as it wicks in easily and sets quickly.

 

[Fergie 307]

Can you take it off? If so I would speak to a local motorcyle or car bodyshop. There are lots of specialists who repair and retexture plastic car and motorcycle parts. Local car or bike workshops will know. A lot of hard plumbing pipe is abs, so the solvent weld glue should work.

 

[scholar]

I have used this stuff quite successfully:
JB WELD 8237UK JB8237 Plastic Weld Fast-Setting Off White Multi Purpose Reinforced Epoxy Putty, 57 G https://amzn.eu/d/2tGgUDW

My application was on PVC downpipes and gutters where I was fabricating some custom angles - first I plastic welded the joints which was structurally ok, but not very pretty (me not being an expert) - then I used the epoxy putty to smooth out the joints and fill the gaps - once hardened fully, I sanded the filled area with a Dremel sanding drum (and then painted - the epoxy putty is white).

I was fairly impressed - you get a reasonable working time - a good 10 mins?

Tried using it with vinyl gloves, but it was easier with bare fingers.

Cheers

 

[scholar]

Funnily enough, I am just fitting these items today.
There were various custom fittings, all adapted from standard parts - this one is to go over a stone plinth course - it was a bit fiddly. Next time I will go to my local car repair guy who is really good at plastic repairs.

Cheers

 

[thikone]

Have used acetone slurry recently to repair Thule roof cargo box. Used natural colour ABS filament for 3d printer as it has no pigment and therefore a bit stronger. Also used glass fibre textile to re-enforce it.

Don't worry about dissolving 1mm of the part that you want to fix, it is not so fast, takes some hours really. But it is better to be unloaded and not stressed while it dries.