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Der findes mange forskellige typer klæbemidler, lim og tape, hver med deres egne styrker og svagheder. Her kan du lære, hvilken type der er bedst til en bestemt reparation.

Resumé

Når ting falder fra hinanden, findes der forskellige typer lim og tape, som du kan bruge til at sætte dem sammen igen, men de forskellige typer er gode til forskellige ting. Denne side vil hjælpe dig med at vælge den rigtige.

Bemærk venligst: Enhver omtale af specifikke kommercielle produkter på denne side betyder ikke, at de på nogen måde støttes eller anbefales af The Restart Project. Sådanne omtaler er blot givet som eksempler til illustrative formål.

Sikkerhed

Brud på elektriske artikler, der er repareret med klæbemiddel og/eller tape, vil nødvendigvis ikke bestå den visuelle inspektion i forbindelse med en basal elektrisk sikkerhedstest. Hvis du beslutter dig for at foretage en sådan reparation (på eget ansvar), bør du i det mindste sikre dig, at limen understøttes af stærk tape, f.eks. Gaffatape med indbygget væv, der er viklet helt rundt om emnet med god overlapning.

Nogle limtyper kan være letantændelige, forårsage hudirritation eller afgive sundhedsskadelige dampe.

Typer af lim

Der findes mange forskellige typer lim. De første nedenfor er de mest nyttige i en reparationssituation, men andre kan være nyttige til generelle reparationer eller til at lave ting.

Læs altid vejledningen, ellers får du måske ikke tilfredsstillende resultater og er måske ikke klar over eventuelle farer.

Superlim

Superlim klæber dine fingre sammen med det samme. Det kan være ret pinligt at skulle på skadestuen for at få dem løst.

Superlim giver en meget stærk samling, hvis de overflader, der skal sættes sammen, passer meget tæt sammen, men det er ikke så godt til at udfylde huller. Køb det i små tuber, prøv at tømme dysen efter brug, og sørg for at sætte låget tæt på, da det ellers sætter sig fast.

Hvis du har brug for at udfylde et hul, kan du bruge superlim og bagepulver. Kom lidt bagepulver i hullet - kun så meget, som du kan gennemvæde med en dråbe superlim, og tilsæt derefter en dråbe superlim. Du kan gentage processen så ofte som nødvendigt for at udfylde et større hul. Det vil i løbet af ganske få minutter hærde til en meget hård og sej fast masse.

Epoxy

Epoxylim kommer i 2 separate tuber, en med harpiks og en med hærder. Pres den samme mængde fra hver tube, og bland godt. Sørg for at sætte det rigtige låg tilbage på den rigtige tube, ellers får du dem aldrig af igen!

Epoxylim er meget stærk og klæber til de fleste ting. Selv om det er bedst, hvis de matchende overflader passer godt sammen, kan du bruge det med forsigtighed til at udfylde huller, men da det er ret flydende, bliver det måske ikke hvor du vil have det. Der findes flere typer epoxymasse, som du kan bruge i stedet. Disse leveres som regel som en pind, der indeholder begge dele. Du skærer så meget af, som du har brug for, og så æltes det med fingrene for at blande det.

Hurtig epoxy hærder på få minutter og er derfor meget anvendelig, selv om det tager længere tid at opnå fuld styrke.

Hot Melt

Hotmelt-lim kommer i stave, som du skal føre ind i en limpistol. Billige limpistoler kan fås for under 100 kroner. Påfør limen, og sæt delene sammen med det samme. Limen hærder i løbet af få sekunder, når den køler af, men det tager lidt længere tid at opnå fuld styrke.

Hotmelt-lim forbliver fleksibel, efter at den har sat sig, og er derfor god til at reparere fleksible ting, f.eks. at klistre sålen tilbage på en sko. Når en ledning er loddet til et printkort, er en klat smeltelim meget god til at forhindre, at ledningen bøjer og knækker ved loddeforbindelsen.

PVA-lim

Denne lim fungerer godt med porøse materialer som papir, træ og stof. Det bruges til håndværk, bogbinding, træbearbejdning og som tapetklæbemiddel. En skruet og limet samling i træarbejde er meget stærk. Du har måske først mødt det i en ung alder som skolelim eller trælim, som er en ikke-vandfast PVA-lim.

Polyurethanlim

Du kan bruge denne til mange af de samme anvendelser som PVA, men den har den fordel, at den hærder på kun 5 - 20 minutter. Du kan også bruge det til at klæbe en lang række materialer. Når det hærder, skummer det op. Pas på: Hvis det kommer på en overflade, som det ikke bør være (herunder dine fingre), er det meget svært, hvis ikke umuligt, at få det af! Findes også under navnene Trælim PU eller Vandfast trælim.

Vinyllim

Dette er godt til at klæbe PVC, da det består af PVC opløst i et opløsningsmiddel. Dette opløser delvist de overflader, der skal forbindes, og danner en svejsning, når det hærder. Fuld hærdetid et døgn.

Latexlim

Latexlim er i bund og grund bare en gummiopløsning. Den kan også findes under navnet Copydex. Fremragende til limning af stof, læder, sko.

Glaslim

Dette er en UV-hærdet lim, som er god til at klæbe glas, gennemsigtig akryl eller metal på glas eller akryl. For at hærde det kan du bruge en UV-lampe eller en UV pen. Alternativt kan du blot lade det ligge i sollys, men det vil dog tage betydeligt længere tid.

Polystyrenlim

Anvendes hovedsagelig til samling af "Airfix"- og lignende plastmodeller, men også til flamingo (styropor) og papir.

Silicone Glue

Silicone filler is most commonly used for sealing around bathroom and kitchen fittings, and around window frames, but can also be used as an adhesive. It remains flexible after it has set but is not especially strong, and surfaces need to be clean and dry. You may see its use in consumer electronics where a blob has been applied to retain a flying lead in position.

Sugru is a type of silicone, described later.

Once opened, a tube of silicone adhesive is difficult to effectively seal. After a few months you may find the nozzle if not the whole tube has set solid.

Flour and water paste

Mix a little flour with water to make a moist spreadable paste. If you have nothing else to hand, this makes a surprisingly good glue for paper, card and fabric and is child-safe.

Sticky Tapes

PVC Tape

PVC insulating tape is good for wrapping around exposed wires and electrical connections, however, it should never be use as the sole protection in the case of mains (or higher) voltages. If two wires are simply twisted together, heat may be generated when a current flows and this could melt the tape. (Use solder or a crimped or screw-secured connection - see Connecting and joining wires.)

PVC tape sticks reasonably well but it's stretchy and not especially strong, so shouldn't be used simply for fixing.

Gaffer Tape and Duct Tape

These are very strong tapes used for holding things together. Gaffer tape has a fabric backing and is designed to be removable; it is often used to tape cables down to avoid trip hazards or to conceal them on stage. Duct tape has a plastic-coated fabric back and is designed to stick permanently: it is used for all sorts of repairs and is waterproof and very durable. The two are similar, are often confused and are interchangeable for many uses.

These tapes are very versatile. It's said that Mission Control knew they had a chance of saving the Apollo 13 crew when they realised they had duct tape on board.

Kapton Tape

A characteristic transparent orange or brown, you may have seen this without realising what it is. Being able to withstand a very wide range of temperatures from −269 to +400°C it's useful for insulation where high temperatures may be encountered, as well as for protecting sensitive parts when using a heat gun for soldering or desoldering. Its weakness is that in the longer term it can be degraded by moisture or by mechanical chaffing.

Self-amalgamating Tape

This isn't strictly adhesive, but when wrapped around an electrical junction or low pressure water pipe the layers fuse together seamlessly.

Heat-shrink Sleeving

A little different though useful in some of the same situations is heat-shrink sleeving. This comes in various diameters and shrinks to half the diameter when heated. Slipping a piece over a wire join is much better than using PVC tape. You can shrink it (ideally) with a hot air gun, or if you don't have one to hand, holding it very close over the barrel of a soldering iron will do it, but you need to be careful not to let it touch.

Stretch-release adhesive

If you've ever changed a smartphone battery or simply glanced at a repair guide for doing so, you will have come across the stretch-release strips that the batteries generally attached to the device shell with. These grip very strongly yet simply by pulling a tab on the end they stretch to many times their original length, releasing their grip in the process.

Similar products are available for general use, such as Tesa Powerstrips, which might be useful now and than in repair. Make sure the two items to be attached are accurately positioned before pressing them together as there will be little or no chance of adjusting them, short of removing the strip and using a new one.

Sellotape and Scotch Tape

These should normally only be used for paper and parcels. In an emergency you can use double-sided sticky tape to secure a smartphone battery within the smartphone shell but if it fails the battery might move and strain its connection to the main board.

Conductive Sticky Stuff

Bare Conductive electric paint

Bare Conductive is an electrically conductive paint which you may be able to use to bridge a broken connection. It has a much higher resistance than copper or solder and so isn't suitable where a low resistance connection is required or where it must carry more than a few mA. It should be fine, however, for connections to an LCD, or to the momentary-contact push buttons on nearly all modern electronic equipment.

A slight problem with it is that once opened, the dispenser dries out over a period of months. You may be able to rejuvenate it if you can unblock the nozzle and introduce a little plain water, then shake vigorously. A hypodermic syringe would be ideal for this.

Conductive Silver Paint

If you need a low resistance join for example to mend a broken circuit board trace then conductive silver paint may well do the job, although it's expensive. Like bare Conductive, once opened it dries out quite quickly, and being solvent based can't so easily be restored.

PCB pads

PCB Pads are not glue but flux coated cobber stribs meant for reaparing a PCB with broken cobber connectors. They are soldered on to the remaining cobber that needs reconnecting.

Other Sticky Stuff

Sugru

Sugru comes in sachets and initially has a putty-like consistency but cures to a synthetic rubber. Excellent for adding protection and strain relief to a low voltage cable (such as a headphone lead) where the outer insulation is starting to crack on its entry to the plug. The website www.sugru.com gives hundreds of other examples of its use. It comes in black or white and several bright colours.

A drawback is that part used sachets can't be resealed and will very quickly go off, and unused sachets have a limited shelf life. This can be extended somewhat by keeping them in the fridge.

You can make your own Sugru-like substance, Oogoo with silicone paste, corn starch and food colour.

Shoe Goo

Recommended by iFixit and others for sealing and patching holes in rubber shoe soles etc, this comes in a tube and cures to solid rubber. Waterproof, with good adhesion to flexible surfaces.

Thermoplastics

Polymorph consists of granules which turn soft when heated to 62 degrees centigrade, then harden again when they cool. The Register described it as 'the stuff of the gods, or would be if it had been around when the gods were choosing a construction material.'

Formcard is essentially the same except that it comes in convenient credit card sized pieces. The idea is that you can easily keep one with you for use whenever you might need it. It can be softened in hot water as required and then can be moulded for a variety of uses before it sets hard on cooling. It was launched in a Kickstarter campaign in late 2015 and is now available from the inventors website.

Fixits are very similar but come in the form of a stick. They appear to soften at a slightly lower temerature.

Epoxy putties

2-part epoxy adhesives are available mixed with a filler to make a putty-like product. The parts may come separately or as a stick with the hardener as a coating along its length. Cut off the required amount (equal amounts of the two parts if separate) and knead them together in your hands until they are thoroughly mixed.

Various different fillers are available, including steel powder, making a product which is extrremely tough when fully set. Milliput is a more general purpose product which comes in several grades intended for different mending and model-making applications.

Epoxy putties may not all bond as strongly to whatever you're mending as strainght epoxy adhesive, so are best for filling gaps.

Modelling Clay

There are several types of modelling clay, mostly used for making rather than repairing. Polymer clay can be cured by heating to a modest temperature of 130⁰C for 15 minutes and doesn't shrink or change shape in the process. It can be obtained from hobby, craft and art stores.

How to remove glue

Sometimes your problem might actually be to unglue something, either because it wasn't glued properly or because you need to disassemble the item for repair. Different glues will respond to different solvents, but two of the best for difficult cases are:

• Acetone (or nail polish remover)
• Proprietary glue removers (search online) such as Z-7 Debonder (acetone-based), especially any advertised for removing super glue.

The most effective glue removers contain heterocyclic ketone, which is a powerful glue remover. (Acetone is a ketone, but not a heterocyclic one. But if you want to know what heterocyclic means, don't ask us. Sign up for a course in advanced organic chemistry.)

Be aware that any solvents may irritate sensitive skin or discolour the glued item, especially fabrics.

External links

• If you're still not sure how to stick X to Y, then take a look at the website This to That.
• Tim Hunkin's video on different types of glue from his series "The Secret Life of Components" is well worth watching.
• Our Restart Radio show "Materials we use to hack and fix"