How to restore discoloured fader caps?

[BelfastGooner]

I just bought a Yamaha O2R 24 (with 2 adat cards and meter bridge for a ridiculously low price) but the 16 white fader caps have all discoloured over time. I was just wondering if theres any safe way to restore these to their original colour, or as near as possible? I saw on one forum, someone was recommending using the "Retrobrite" method of hydrogen peroxide and UV light. Others, however, say this will turn the plastic to dust and not to use it.

Any help or suggestions appreciated.

[Mike Stranks]

Bit of a sideways approach, but often on eBay you'll find people selling-off various knobs and fader-caps from mixers that they've disassembled...

... just search 'Mixers' in 'Pro Audio Gear'.

[Martin Walker]

Yes, I've seen suggestions of hydrogen peroxide, although I'd be careful with that one.

The gentlest way to try at first is with warm soapy water and an old toothbrush before you investigate fiercer approaches.

[Sam Spoons]

In the sailing world we use oxalic acid solution to remove rust stains from sailcloth and GRP, not sure whether it would work with whatever plastic used to make fader caps though. That said if you could source a few spares off ebay they will likely be similarly discoloured so you could experiment with different approaches.

I'd also start with soapy water and a toothbrush though (as MW says).

[James Perrett]

Try putting them in the washing machine. This worked well to restore the knobs on my A&H desk to their full glory. I put them in a washing bag first though and I think I used a fairly gentle setting.

[Wonks]

You could just get a can of spray paint and spray them after cleaning them in soapy water, if that initial cleaning doesn't work.

[OneWorld]

I just bought a Yamaha O2R 24 (with 2 adat cards and meter bridge for a ridiculously low price) but the 16 white fader caps have all discoloured over time. I was just wondering if theres any safe way to restore these to their original colour, or as near as possible? I saw on one forum, someone was recommending using the "Retrobrite" method of hydrogen peroxide and UV light. Others, however, say this will turn the plastic to dust and not to use it.

Any help or suggestions appreciated.

Yep you have to be careful what you use for cleaning. I thought meths was quite ‘benign’ and so I thought I would use it to clean my Virus TI and ended up wiping off the text for the controls

[orange]

I've used hydrogen peroxide on yellowed fader caps - took about an hour. I didn't use UV but left them to soak out in the garden on a sunny day.

It worked perfectly and came out totally white. No damage to the black printed line.

I also used it on some other coloured fader caps and also helped them look much better too.

They didn't melt/turn brittle/disolve/turn to dust

That was about a year ago and they still look white and haven't re-yellowed.

[Wonks]

I've used hydrogen peroxide on yellowed fader caps - took about an hour. I didn't use UV but left them to soak out in the garden on a sunny day.

So you did use UV.

[orange]

I've used hydrogen peroxide on yellowed fader caps - took about an hour. I didn't use UV but left them to soak out in the garden on a sunny day.

So you did use UV.

hence why I pointed out it was a sunny day

[BelfastGooner]

I've used hydrogen peroxide on yellowed fader caps - took about an hour. I didn't use UV but left them to soak out in the garden on a sunny day.

It worked perfectly and came out totally white. No damage to the black printed line.

I also used it on some other coloured fader caps and also helped them look much better too.

They didn't melt/turn brittle/disolve/turn to dust

That was about a year ago and they still look white and haven't re-yellowed.

So did you use neat hydrogen peroxide, or did you dilute it?

[BelfastGooner]

I've used hydrogen peroxide on yellowed fader caps - took about an hour. I didn't use UV but left them to soak out in the garden on a sunny day.

So you did use UV.

I have a UV light which came with a UV activated screen protector. It has 2 rows of 10 tiny UV leds. I'm just wondering if this would be safer to use than a whole day's worth of sunshine.

[orange]

So did you use neat hydrogen peroxide, or did you dilute it?

I bought a small bottle of 9% hydrogen peroxide from the local chemist for about £2...didn't dilute it any further.

And as I mentioned it didn't take 'a day' - was done in about an hour. You could almost see it working.

I really don't think there is any need to overthink it - I know there are lots of different types of plastic but the bottle that the peroxide came in from the chemist has a plastic cap. If it was so caustic to plastic products then I suggest we'd know about it by now

[BelfastGooner]

I really don't think there is any need to overthink it - I know there are lots of different types of plastic but the bottle that the peroxide came in from the chemist has a plastic cap. If it was so caustic to plastic products then I suggest we'd know about it by now

Yeah, but there are so many different molecular structures of plastics, that what be fine for one type, may be totally destructive for another.

In the end, I've ordered a set of 20 white caps, 10 greys and 10 whites from Aliexpress. I can live with the originals until these arrive. And if they're crap, which there is every chance they will be, I'll have a go at the hydrogen peroxide method.

[orange]

Yeah, but there are so many different molecular structures of plastics, that what be fine for one type, may be totally destructive for another.

I totally understand, they are your fader caps and obviously it's your call ......although you did come here to ask for advice...and advice was given, feel free to ignore though.

I really can't see any danger giving them a soak. Any plastic that your fader caps will be made from will be 100% fine. Hydrogen Peroxide liquid that you can buy over the counter in the UK is pretty weak. I used 9% which was the strongest they had.

People use it as a mouthwash, or whiten teeth with it (!) OxyClean is also hydrogen peroxide - you use it in your washing machine with all those rubber and plastic parts. It's really not going to melt your fader caps if you dip them in there for an hour or two. No more damage than you would get from the UV if you left it in the sun for an hour. UV is far more damaging to most plastics than H2O2.

[Kwackman]

In the end, I've ordered a set of 20 white caps, 10 greys and 10 whites from Aliexpress. I can live with the originals until these arrive. And if they're crap, which there is every chance they will be, I'll have a go at the hydrogen peroxide method.

It looks like you can still buy the original yamaha ones.
https://www.proaudioservice.co.uk/produ ... -vr27560r/

[N i g e l]

Ive not used the hydrogen peroxide method, for knobs off ebay. I tend to put the knobs in a bag in the washing machine & enjoy the original patina that comes with age.

The exception was my Yamaha MG mixer, which I replaced the slider knobs with modern rubbery feel ones from Rapid or RS. They look mechanically similar to Kwackmans spare parts.

Hydrogen peroxide is readily available in various grades of dilution, not least as a food stuff distantfectant. Last stuff I bought was from a place in Glasgow that also sell small quantities on ebay.
Although for £1 more you get double the volume.
I think I went for 1L in the end - I used to buy cheap fungal infected camera lenses off ebay and make them good for my own use.

[Mike Stranks]

Looks like there's been some misunderstanding about my 'have a look on eBay' comment...

I didn't mean that the OP should replace his discoloured caps with other discoloured caps purchased from there and then try and brighten those up...

... simply that I often see on eBay used caps, knobs etc of all styles from multiple older mixers that look perfectly fine. If cleaning wasn't successful, then searching those for the requisite items might have been a solution.

But I see that someone has now identified a source of replacement caps for this mixer...

As you were...