How to stick things

This "how-to" came from the following question. Although the question relates to plastics, the answer is generally applicable. The apparently elementary job of sticking two things together with glue or gum or adhesive is far more complex than you might imagine. Read on.

Q: I am looking for some means of sticking plastic to plastic; I have tried most store available options including epoxy. Are there any others that might work?

A: It might help to know which plastic it is, how much load the joint has to take, and how many pieces you need to join. Some surface preparation may be needed, sometimes as simple as cleaning or sandpapering, but sometimes using extreme methods like plasma etching or activation with sodium metal (needless to say, this is for experts only).

With this, and with the right glue, even the famous non-stick plastic (PTFE or Teflon-tm). can be made to stick. In fact a popular marketing line of the glue industry is ' we mend everything but broken hearts ' !

Also important are: amount, placement and distribution of the adhesive (which may need special dispensing equipment); alignment and clamping of the workpieces; clenliness of the environment (dust, humidity); temperature of the adhesive and workpieces; and curing conditions (temperature and humidity of the environment).

If you wish to search, start with Loctite, which is a company that makes a wide variety of speciality glues: search for them on the web. Closer home, Pidilite makes a range of glues too. Amongst the glues you can buy easily in the market are: white glue (Fevicol), epoxy (Araldite, in normal and rapid setting versions, and in various viscosity ranges, e.g. M-seal), rubber cements (Stickfast, Fevitite, Speb), cyanoacrylates (superglue, crazyglue, Feviquick), gelatin-collagen glues, natural gums (gum arabica, rosin, beeswax, canada balsam), starch (rice-paste), cellulosic derrivatives (laquers like cellulose nitrate and acetate), silicones (RTV) and hot-melt adhesives (Pidilite).

How to un-stick things: this is equally complex, expecially if you do not want to damage the items (particularly the surfaces) involved. It is better to take this into account when choosing an adhesive. Some hot-melt adhesives work well for this, if you are willing to heat the items involved.