Superglue and soft plastic.

[Gern]

Hi guys, I'm back with a question on this old chestnut.

I need to glue some polyethylene type plastic - similar to that used by Airfix for their 1/72 figures. I've bought a two-part CA glue which works for the figures but it doesn't work on the bits I'm trying to stick.

Here's the fun part though. I can use ordinary CA glue (Expo Red Label) to glue the soft plastic to styrene - so the glue will obviously adhere to the soft plastic right? So how come it doesn't adhere when I use it to try and stick two pieces of the soft plastic together?

[Guest]

One thing to remember with these polyethylene/polythene parts is that they tend to have a lot of release agent on them. A really good wash in warm soapy water is essential first to ensure you are applying the glue to the plastic. After that I would rub the surfaces with a fine wet and dry to give the glue a better key to grip and you are giving the parts the best chance of adhereing. This stuff has always been notoriously difficult to glue but the above will give you the best chance. It might be wirth considering either a mechanical fixing such as a screw or a nut and bolt, where appropraite or even plastic welding might be a possibility.

[Guest]

CA needs a certain amount of moisture to cure. Perhaps as the two of soft plastic exclude moisture then it will not set. You could try an accelerator that may ! do the trick.

Just taken a £1 subscription for a month on Which which has an article on CA glues. Will have a look and see if there is any info there.

Laurie

[Ian M]

With regard to the glue working when you stick the soft plastic to hard. It could be that it is not the "glue" that is sticking... The melted polystyrene might in some way be bonding to the poly-in the softer plastic.

Which raises the question that if the parts to be glued are not to small could you make a gunk of poly glue and sanding dust from polystyrene to use as glue....?

Ian M

[Guest]

Dave. Locktite do a CA for soft plastics.

No mention of soft plastics in Which. You would have thought in testing the glues they would have tried a variety of materials.

One thing that did come out of their tests and that is that Locktite came top with all their frontline CAs. Poer Drop was not tested but in my expereince having used Locktite and PowerDrop I have found PowerDrop the best. Except that Locktite has an easier method of decenting.

Laurie

[Gern]

Thanks guys. Some nice thoughts there which I'll be playing around with. I'll let you know how I get on.

[Ian M]

Well if the info on this web site is solid it looks to me like you will earn a fortune if you figure it out. Apparently there is no glue upto the job. Polyethylene was designed to resist chemical solvents...

http://www.eplastics.com/Polyethylene-Adhesives-Glue

Ian M

[Gern]

Doesn't look too promising then Ian!

The pieces I'm working with originally had paper stickers all over them - you know the sort. The shiny ones that tear apart rather than lift off the plastic cleanly. Then you have the devil's own game to remove the glue residue! I had to sand mine clean. I wonder what glue they use on those stickers?

[Guest]

I would try Evostick Impact: Instant Contact Adhesive.This is the stuff used for sticking kitchen laminates to the chipboard. (At least it was used 15 years ago.) It is sticky on exit from the tube and this can be useful. It dries in about 10 minutes whereupon it adheres instantly and irreversibly (again useful). During that 10 minutes it can be repositioned (also useful). In over 30 years of use for various household tasks I have found only one plastic that refused to stick to it.

I have just done a test. I put some Evostick on to a (probably polythene) Tupperware-like kitchen box and on to a plastic household bucket, and on to two objects (actually spent AA batteries), waited for 10 minutes and they stuck like the proverbial. In fact, I had a lot of bother stripping the residue from the box. As that is our biscuit box I was in danger of real trouble, but I got it off after some effort. What's the betting she will detect the smell of the solvent?

[Guest]

Well if the info on this web site is solid it looks to me like you will earn a fortune if you figure it out. Apparently there is no glue upto the job. Polyethylene was designed to resist chemical solvents...http://www.eplastics.com/Polyethylene-Adhesives-Glue

Ian M

Hence the plastic welding or the mechanical fastenings suggestion. A soldering iron can make a useful welding tool for plastics, assuming of course you have the availability of the edge of the joint to work with.