Retrobriting is a controversial topic I know, and I've had my own successes and failures. I once tried the peroxide cream method on a pale coloured Japanese SEGA Saturn and ruined it with streaking. Other smaller parts I've treated in liquid peroxide - like a Nintendo GameCube front panel and WaveBird controller - only for them to return to looking yellowed a year later. So these days I don't think it's worth doing, but...
My recently acquired Amiga 600 was in a fairly typical dirty state and cleaned up pretty well. The protective film was still in place over the C= logo and the warranty sticker had never been poked. Good signs. Overall it was pretty un-yellowed, but what I started to notice was that the only yellowing was in the following places:
When I had an A600 in 1996 I noticed a sort of yellowing thumbprint on the edge of the keyboard which I unsuccessfully tried to bleach, and ultimately I spoiled the plastic texture by scrubbing it too much. On my recently acquired A600 I had a lot of yellowing on the underside of the machine, around the trapdoor and a literal handprint. Since it was underneath and not very visible I took a chance by painting on a very thin film of peroxide cream only onto the affected areas and leaving it in the sunshine. I found that after only a couple of 10 minute exposures the yellowing was gone. For the bit near the keyboard I found that a very light rub with a magic eraser lifted the yellow off completely. So it seems that although fingerprint oils can interact with and yellow ABS, they tend to do so on a very surface level - which does seem to be very treatable, without resorting to peroxiding the entire thing. A sort of 'remedial peroxiding' or 'retrobrite lite'.
The yellow can't be seen very well in the 'before' photos (from the for sale listing), but I've marked up where the palm print was in red. Aside from the very quick peroxide treatments, unscented baby wipes work really well for case scrubbing, and Magic Eraser on the stubborn case scuffs.
Before. This isn't only dirt - there a lots of yellow patches (around the feet, and the spread handprint ringed in red):
Below is the result after cleaning and very quick peroxide cream exposures to the sun for 20 mins, with a thin enough coat to just barely wet it but only on the actual yellowed areas, feathering with the brush to avoid any edge lines. I did 2 x 10 mins, checking carefully. The rubber feet remain the original ones, just cleaned up with alcohol and a rub of silicone grease.
Before and after for the rest of the case:
The area just under the edge of the floppy drive was very yellow, because it's handled the most. Sadly I didn't photograph that, but the same method worked (slightly more exposure). The area around the Help key and the second A in Amiga were lightly yellowed, but this light layer came of with a very light rub with a Magic Eraser.
My recently acquired Amiga 600 was in a fairly typical dirty state and cleaned up pretty well. The protective film was still in place over the C= logo and the warranty sticker had never been poked. Good signs. Overall it was pretty un-yellowed, but what I started to notice was that the only yellowing was in the following places:
- Where fingerprint oils have made contact with the ABS - for instance all around the floppy drive, in particular under it, and on the edge of the keyboard under the cursors.
- Where the plasticiser in the rubber feet has interacted with the ABS
When I had an A600 in 1996 I noticed a sort of yellowing thumbprint on the edge of the keyboard which I unsuccessfully tried to bleach, and ultimately I spoiled the plastic texture by scrubbing it too much. On my recently acquired A600 I had a lot of yellowing on the underside of the machine, around the trapdoor and a literal handprint. Since it was underneath and not very visible I took a chance by painting on a very thin film of peroxide cream only onto the affected areas and leaving it in the sunshine. I found that after only a couple of 10 minute exposures the yellowing was gone. For the bit near the keyboard I found that a very light rub with a magic eraser lifted the yellow off completely. So it seems that although fingerprint oils can interact with and yellow ABS, they tend to do so on a very surface level - which does seem to be very treatable, without resorting to peroxiding the entire thing. A sort of 'remedial peroxiding' or 'retrobrite lite'.
The yellow can't be seen very well in the 'before' photos (from the for sale listing), but I've marked up where the palm print was in red. Aside from the very quick peroxide treatments, unscented baby wipes work really well for case scrubbing, and Magic Eraser on the stubborn case scuffs.
Before. This isn't only dirt - there a lots of yellow patches (around the feet, and the spread handprint ringed in red):
Below is the result after cleaning and very quick peroxide cream exposures to the sun for 20 mins, with a thin enough coat to just barely wet it but only on the actual yellowed areas, feathering with the brush to avoid any edge lines. I did 2 x 10 mins, checking carefully. The rubber feet remain the original ones, just cleaned up with alcohol and a rub of silicone grease.
Before and after for the rest of the case:
The area just under the edge of the floppy drive was very yellow, because it's handled the most. Sadly I didn't photograph that, but the same method worked (slightly more exposure). The area around the Help key and the second A in Amiga were lightly yellowed, but this light layer came of with a very light rub with a Magic Eraser.
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