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There is a huge number of glues on the market covering everything from imitation metals to water thin transparent adhesives and the range is increasing almost daily. For the modeller this can be a confusing array so here are the basic types:
Polystyrene Cement / Plastic glue
These are the standard model glues used for glueing plastic kits and were the only option for years. There are great many varieties on the market and they all work in the same way. The glue is air drying so when it is dispensed in thin layers onto the plastic it starts to dry staright away. Whilst this is happening on the surface of the glue, so that it starts forming a skin like paint or custard, the glue that is in contact with the plastic starts to melt the material. If you put too much glue on a model it is not unusual to find that the plastic starts to dissolve and change shape! So with a thin layer on each of the two surfaces, when they are placed together you are actually pressing two melting surfaces together. As the glue dries and the plastic stops melting, the two pieces weld themselves together into one. This is an irreversible process and once the glue is on there is not much you can do to remove it without a fair amount of effort.
All the major kit manufacturers market their own versions of plastic glues and they come in a variety of dispensers. Some come in bottles with a brush attached to the inside of the top so one can brush the glue on with more control and accuracy. Another popular alternative comes in a plastic bottle with a very fine needle tube so that the adhesive may be dispensed in very small amounts. The most common way to buy glue is still in the tradition tube (normally about 12ml / 10 grams) with a screw cap or open nozzle. Most modellers are familiar with this type of tube and it all comes down to personal prefernce in the end. Whatever dispenser you are happiest with is likely to give you the best result. As ever, its horses for courses and if in doubt or unfamiliar then experiment on scrap.
Italeri Poly Cement
Epoxy Resin Glues
Unlike the above glues, the principle of epoxy resin is based on a chemical reaction. It is a two part adhesive that needs thoroughly mixing before use. One part is the adhesive and the other is the Hardner, Curer or Catylist. When the two parts are mixed they start a chemical reaction resulting in the two liquids setting hard. Often this glue dries yellowish and has the habit of spreading its colour through paint layers so make sure you get a colourless type if its going to be on a painted surface.Traditionally these glues have a very long curing time, maximum strength being reached in three days! They are a development from the adhesives that were used on aircraft in World War Two and are actually based on a bizarre centuries old Swiss watchmakers glue! ( For those who are sad enough, like me, to be interested I have listed the recipe for this glue at the end of the article) The most recognisable name in this field is Araldite, from the Swiss company, Ciba-Geigy although today there are numerous manufacturers and as ever experimentation is the key.
Many varieties of this are now available, including rapid drying versions which, in some cases, is down to a matter of minutes. It was always said that fast drying glues were not as strong as the slower curing types. From my experience this certainly used to be true but with so much on the market and so much technical development this is no longer necessarily the case. It is a market where new products are appearing the whole time so keep your eyes open and watch out for revues. Most model shops stock versions of these glues from established manufacturers, and DIY stores, Car Spare Stockists and hardware outlets often have a range of them.
The drawbacks to this type of glue is that you need to mix it before use and support the joint whilst it dries. Also, to clean off excess glue from model, hands or table takes a spirit, like White spirit or turps. Once its dry, however, it is a different story and is difficult to remove. It can be slowly dissolved with continual application of methylated spirits or a methyl based paintsrtipper. Unfortunately this sort of treatment is likely to severely damage, if not totally destroy any plastic kit! One the plus is that it is normally quite happy accepting colouring should tinted glue be called for.
It is supplied in a variety of dispensing options the most common being two seperate traditional glue tubes or a double syringe type dispenser, in a variety of sizes.
Araldite
Pcyano-acrylllic / superglues / Instant glues
The technology of these glues has been around for a long time and its not a million miles away from the materials used in cosmetic dentistry. When Superglue 3 was released twenty or so years ago there was much concern at it being dangerous because of its immense bonding power and hyper quick drying time.This, of course, is precisely why modellers are increasingly drawn to this type of glue. It is also the glue of choice for most people who use resin parts or kits, as plastic glue doesnt work at all and the speed of drying and good adhesive qualities, especailly on the heavier resin components, is ideal. This can also be a huge drawback because when attaching resin, or even expensive metal etched parts, you only get the one chance to stick the piece on correctly. With plastic glue, as it cures more slowly, one can move the pieces about to gain the best fit. With cynano glues the adhesion is instant, and that normally means instant! If you use these glues, practice dry assembly on the bits as often as you need to until you are completely comfortable with what you are doing before you start glueing. Once you glue it, it stays glued, so if its in the wrong position then youre lumbered! Many people take chances on parts fitting first time and cant be bothered with practising the assembly dry to start with. Often this works but why take the chance? How annoyed are you going to be if the etched metal grill part is 2mm away from where it should be and looks aweful?
There are drawbacks to superglue as well. Cynao-acryllic glues are ulltraviolet hydroscopic glues. In English this means that they are cured by absobing water and exposure to ultra violet light. This means that if you are gluing two dry, and maybe porous, surfaces its a good idea to moisten the contact areas to give the glue something to absorb. Breathing on the joined surfaces once the glue is applied can also help by introducing more moisture to the bond. Only put the glue on one surface. The reason for this is simple. The glue dries very quickly and it does not adhere well to itself. Thus by putting glue on both surfaces you are effectively gluing the glue to itself and not to the component.It also makes the potential joint thicker.
The other problem for this glue user is that because it goes off with water absorbtion, once the tube is open it tends to have a limited life span. As it absorbs moisture from the atmosphere it will work less effectively and as time goes on it will develop a white "crust" . At his stage I normally throw mine away!! Special solvents are also needed to undo these glues and it might be a good idea to have some nearby in case of accidents and disasters. It is not uncommon to hear of people gluing fingers to tables or kits!
ELFY SuperGlue
Swiss watchmakers Glue Recipe!
This is an actual recipe that I heard about thirty years ago and completely disbelieved until about ten years ago, I saw it in writing in a book, published in 1902 .
Take an equal weight of shelled snails and gruyere cheese ( I joke not! Dont worry, it gets worse! ) and simmer them together for twenty four hours. Next add a quantity of beer, about half a pint, stir it in and simmer for a further twenty four hours. After this you have twelve hours to use it before it sets. When it set its like concrete. I never found a solvent for it and could only remove it with a grinder! Before it sets it is recommended that you roll it out to a depth of about an inch and score it into squares. When it has set you can break off these squares with a hammer (!), reheat them on the stove and at the appropriate time use the glue when it is mallable enough. I have never made this glue but heat didnt touch the stuff I came across! Believe it or not but this is an early organic version of epxoy resin!
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