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A surprising share of "broken" electronics are not broken. They have a dirty contact.

Singapore makes this worse than almost anywhere. Humidity sits around 80 percent most of the year, and every time a room is cooled and then warmed again, moisture condenses on metal. On a copper or tin contact, that leaves oxide. On a brass or gold-plated one, it creeps in at the edges. The result is a connection that is electrically poor without looking broken — which is exactly the kind of fault that gets a working part thrown away.

Rexco 18 Specialist Contact Cleaner exists for this one job. Here is how to use it properly.

Why it has to dry instantly

This is the whole design of the product, and it is what separates a contact cleaner from every other spray on the shelf.

A contact cleaner has to do three things at once. It must dissolve oxide, grease, flux residue and grime. It must not conduct electricity, so it cannot bridge adjacent pins. And it must evaporate completely, leaving nothing behind at all.

That last point is the one people underestimate. Any film left on a contact becomes a dust magnet, and dust on a contact is the original problem again in a few months. A residue can also be slightly hygroscopic, meaning it attracts the very moisture you were trying to get rid of.

So "quick dry" is not a convenience feature. It is the specification. Rexco 18 flashes off in seconds, leaves zero residue, is non-conductive and non-corrosive, and is both acetone free and chlorine free.

Do this first, every time

Power off. Unplug from the wall. Remove the battery if there is one. On a desktop PC, switch off at the PSU and hold the power button for a few seconds to discharge.

The fact that the fluid does not conduct is not permission to spray a live board. Shorting is only one of the risks; the other is that a powered component can be damaged by thermal shock from a cold evaporating solvent.

Then work somewhere ventilated. Open a window or work at a bench with airflow. This is a solvent, and in a closed, aircon-sealed room the vapour builds up more than you would think.

And let it dry fully before powering back on. Seconds, not minutes, but give it those seconds.

Computers: where it genuinely helps

RAM and expansion card edge connectors. The classic. A PC that will not POST, or boots with less memory than it should, very often just has tarnished gold fingers. Remove the module, spray the edge connector, let it flash off, reseat it. This fixes more machines than it has any right to.

Internal headers and power connectors. Front-panel headers, fan headers, SATA power. Connectors that get plugged and unplugged, or that sit in a warm case pulling dusty air through for years.

Card edge slots. A short burst into the slot, then let it drain and dry with the board on its side so nothing pools.

Keyboards. For a sticky or unresponsive key on a mechanical board, lift the keycap and give the switch a short spray, then work the switch a few dozen times while it is wet. On a membrane keyboard this is less reliable, because the problem is usually the membrane itself rather than a contact.

Beyond the PC

The same can earns its keep across a lot of other things.

Scratchy volume knobs and faders on amplifiers, mixers and guitar pedals. Spray into the pot, then rotate it through its full travel twenty or thirty times. The crackle usually disappears entirely.

Audio jacks and HDMI ports that need wiggling to work.

Remote controls and key fobs — battery terminals go green here faster than most people expect.

Control panels, relay bases and DB terminals. In a plant room or a non-aircon workshop, humidity and dust make intermittent faults routine. Before you order a replacement relay or contactor, clean the contacts. It is right often enough to be worth the two minutes.

Vehicle and motorcycle connectors. Multi-plugs, bulb holders, kill switches, ignition connectors. We cover this in more detail in our motorbike maintenance guide, because in this climate it is the single most common cause of an electrical gremlin.

What not to use it on

This is where honest advice matters more than a sales pitch.

Not a screen cleaner. Never spray it on an LCD, OLED or phone screen. Display panels have anti-glare and oleophobic coatings that solvents will strip, and the damage is permanent and very visible.

Be careful around plastics. Some solvents can craze or cloud certain plastics, particularly clear polycarbonate and acrylic. Aim at the metal contact, not the housing. If overspray onto a visible plastic surface is unavoidable, test on a hidden area first and wipe promptly.

Not for dust. If the problem is a case packed with dust, a solvent is the wrong answer — it turns dust into sludge. Use a blower or a vacuum first, then use contact cleaner on the contacts afterwards. The two are complementary, not alternatives.

Not on rubber and belts you care about, and not as a general degreaser. For greasy machinery, Rexco 70 is the right can.

Not a substitute for a general lubricant either. And just as importantly, do not go the other way: never use Rexco 50 or a general-purpose oil on an electrical contact. It leaves a film, the film collects dust, and the fault returns worse than before. This is the single most common mistake we see.

Be realistic about what it fixes

Contact cleaner fixes dirty contacts. That is all it does.

It will not revive a failed capacitor, a dead PSU, a cracked solder joint, a corroded trace that has eaten through, or a board that has had liquid through it and sat wet. If a connector is visibly green and pitted rather than just dull, the metal is gone and cleaning will not bring it back.

The rule we use: if the fault is intermittent, or it comes and goes when you wiggle something, clean the contacts first. If the fault is constant and total, it is a component, and no spray will help.

How to use it, in order

Power off, unplug, remove the battery. Blow or vacuum loose dust away first. Shake the can. Hold it upright and spray a short burst directly at the contact, not the surrounding housing. Work the connector or switch a few times while it is still wet, which is what mechanically lifts the oxide. Let it evaporate fully. Reassemble and test.

It comes in 220ml and 500ml. The 220ml is right for a toolbox or a desk drawer; the 500ml for a workshop or a maintenance team.

Storing it safely

It is a pressurised aerosol. Keep it out of direct sun and out of a parked car or van during the day — the inside of a closed vehicle here gets far hotter than most people realise. Keep it away from anything that sparks or runs hot, and use it with ventilation even though it is chlorine free and acetone free.

If you are not sure which can you need

We stock six Rexco products and the numbers tell you nothing on their own. Our guide to what each Rexco number does lays them out, and if you are weighing this up against the other brand we carry, see WD-40 or Rexco.

Come and get one

Both showrooms carry the full Rexco range. Describe the fault and we will tell you whether a can will fix it — including when it will not.

645 Geylang Road, Singapore 389575 — +65 6546 7446
2 Gambas Crescent #03-19, Nordcom Two, Singapore 757044 — +65 6255 3446

WhatsApp +65 8978 9808, or browse the full Rexco range.