LEGO model?

[Bo’sunParticipant @bosun58570]

Good morning,

Apologies for stretching the theme of Model Engineering.  My question relates to LEGO Technic.

I bought a second hand LEGO Technic Super Car (no, not the 1960’s Gerry Anderson creation), but an extremely good AWD model, with differentials, 4 speed gearbox, steering and suspension, etc.

I suspect the previous owner had spent quite some time building the model, and not wanting to break it down any time soon, has left it on a sideboard or window sill.  The vast majority of the model is fine, but the bright white wheels have degraded to a creamy white colour.

My understanding is, they are made from ABS.  Can they be resurrected by either cleaning or repainting.  If so, does anyone have any suggestions?

[ShugsParticipant @shugs]

Good morning, this is off the top of my head, first thing in the morning, so please treat with caution!!

In football stadiums etc they refresh to plastic? seat by heating them.

Like I have said please treat with caution and find someway of testing first.

Shugs

[John HaineParticipant @johnhaine32865]

Dishwasher?

[Grindstone CowboyParticipant @grindstonecowboy]

I have seen restorations of various plastic parts that have yellowed by treating them with hydrogen peroxide. Never done it myself, though, and unsure if there may be side-effects like brittleness.

Rob

[Russell EberhardtParticipant @russelleberhardt48058]

Heating can be good for dark colours that have faded but won’t work on white plastic that has oxidised.  The way to restore that is to immerse it in hydrogen peroxide solution and leave it out in the sunshine for a few hours.  You’ll have to wait until the summer to get a good dose of short UV radiation.

Russell

[DC31kParticipant @dc31k]

The technique using hydrogen peroxide has acquired the name ‘retrobrite’. On youtube, a channel called ‘The 8 bit guy’ discusses it.

You can buy a UV LED light for use in winter. Take appropriate precautions to protect your own vision.

Wrapping the transparent container in which the parts are immersed in aluminium foil helps reflect the UV so all faces of the item are exposed to it.

[David JuppParticipant @davidjupp51506]

One possible cause of yellowing of plastics is reaction of small amounts of oxides of Nitrogen in atmosphere with the anti-oxidants which are added to the polymer.  Historically this has been an occasional issue in warehouses (NOx from forklift truck exhausts).  A pink discoloration is also possible.

This type of yellowing can be reversed just by exposure to UV – sunlight on a windowsill for a few days can be enough.

There’s a possibility that you may not need the hydrogen peroxide mentioned above.

[Shugs]

On Shugs Said:

 

In football stadiums etc they refresh to plastic? seat by heating them.

That’s also a dodgy car dealer’s technique for briefly refreshing faded black plastic trim.

[SillyOldDufferModerator @sillyoldduffer]

Um, Bo’sun may have to experiment.

Got the same problem with 30 year old yellowed bell-wire.  A good clean didn’t help, Peroxide next, but I don’t have any,

UV light and heat might be the cause, so more might make the yellowing worse.  Or better!  Depends on the plastic and we don’t know what it is.

Peroxide is a mild bleach, so no harm trying.  Won’t go deep though and don’t rush the process.   Try wrapping the wheels in kitchen towel soaked in Peroxide and leave for a few hours to see what happens.

Mechanical cleaning might help, Sodium Bicarbonate scrubbed on via a dampened toothbrush.  (Didn’t work for me!)

I’m avoiding anything chemical that might damage my wire.  Though unsightly it works and replacing it would be a right pain.  Might hide it with paint or white electrical tape.

Dave

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