Retrobrite
Retrobrite (also written Retr0bright or retrobright) is a hydrogen peroxide process used to lighten yellowed ABS plastic on old computers and consoles. The plastic is coated with, or immersed in, hydrogen peroxide and exposed to ultraviolet light, usually sunlight, or to heat. The name and the original formula, hydrogen peroxide with a small amount of an "Oxy" laundry booster as a catalyst and a UV lamp, came from members of the English Amiga Board in July 2008.[1]
The only long-term comparison published so far went against the process. Shelby Jueden (Tech Tangents) treated the top and bottom of a Sega Dreamcast case with peroxide and sunlight in 2015, with part of the underside covered by tape. Ten years later the treated plastic was more yellow than the covered, untreated area, and showed streaks and blotches.[2][3] It is one case from one owner, not a controlled study.
Warning: hydrogen peroxide at 8 % and above is classified as causing serious eye damage. Salon developer at 9 % and 12 % is in that class. Wear goggles.[4]
Why ABS yellows
[edit | edit source]The explanation usually given in the hobby is that a brominated flame retardant in the plastic oxidises with light and heat, and Jueden repeats it in his video.[2][3] Polymer research describes the discolouration as photo-oxidation of the plastic itself. In ABS the polybutadiene rubber phase is degraded first, which causes discolouration and a loss of impact strength. In one laboratory study, UVA exposure behind window glass, chosen to mimic ABS in electrical equipment, embrittled the exposed surface, cut its impact strength and raised its yellowing index.[5]
Hydrogen peroxide strengths
[edit | edit source]Hair developer is sold by "volume". The EU cosmetics regulation, retained in UK law, caps hair products at 12 % hydrogen peroxide, which it equates to 40 volumes, and requires the label to say "wear suitable gloves" and "avoid contact with eyes".[6] Hair bleaching creams at 9 to 12 % are the usual retrobrite chemical.[7]
| Strength | Classification |
|---|---|
| Below 5 % | Not classified for eye effects |
| 5 % to under 8 % | Eye Irrit. 2, H319 "causes serious eye irritation" |
| 8 % to under 35 % (includes 9 % and 12 % developer) | Eye Dam. 1, H318 "causes serious eye damage" |
| 35 % to under 50 % | Eye Dam. 1 H318; Skin Irrit. 2 H315; STOT SE 3 H335 "may cause respiratory irritation" |
| 50 % to under 70 % | As above with Skin Corr. 1B H314 (severe skin burns) and Ox. Liq. 2 H272 (oxidiser) |
| 70 % and above | Skin Corr. 1A H314 and Ox. Liq. 1 H271 (may cause fire or explosion) |
Safety
[edit | edit source]- Wear goggles and chemical-resistant gloves. Hair developer carries the cosmetics regulation's own glove and eye warnings.[6][4]
- If peroxide gets in an eye, flush it with running water for 10 to 15 minutes, holding the eyelids apart, and get it seen by a doctor. Wash skin contact off with plenty of water.[4]
- Keep peroxide away from acetone, alcohols, ammonia, alkalis and metals; it reacts violently with them, and iron, copper, brass and zinc are listed as incompatible materials.[4]
- Keep it in its original container, out of sunlight, and do not decant it into a container that seals; the safety data sheet says not to keep the container sealed.[4]
- From 35 % the classification adds respiratory irritation, and from 50 % skin burns and oxidiser hazards. Use developer rather than laboratory-strength peroxide.[4]
Methods
[edit | edit source]No method has a published, controlled treatment time. Owners judge the result by eye as the work goes on.
Developer cream and sunlight
[edit | edit source]Hair developer cream is brushed over the part in repeated coats and the part is left in bright sunlight for a few hours.[7] Peroxide and sunlight was the method used on the Dreamcast in the ten-year comparison.[2]
Immersion
[edit | edit source]The part is submerged in a dilute peroxide solution and exposed to light. In March 2008 the CBM Museum in Wuppertal found that immersing yellowed parts in hydrogen peroxide for a few days partly reversed the yellowing. German Amiga users took the idea up, and members of the English Amiga Board developed it into the Retr0bright formula.[1][8]
Sodium percarbonate
[edit | edit source]"Oxy" laundry whiteners contain sodium percarbonate, which releases hydrogen peroxide in water. Terry Stewart dissolved 500 g of a whitener with 35 % sodium percarbonate in about 15 to 20 litres of water and left Apple Lisa keyboard cases in it in New Zealand summer sun for 4 to 8 hours; he judged the result about 95 % of the way to the original colour, in a trial with no comparison against peroxide.[9]
Sunlight alone
[edit | edit source]Dave Farquhar left a yellowed Apple II disk drive in the June sun in Missouri. The side facing the sun lightened noticeably after about 12 hours, and after six days the drive was close to, but not quite, its original colour; a patch that had been under a label kept the original colour throughout.[10] It is the slowest method and adds no oxidiser.
Heat, ozone and other methods
[edit | edit source]Jueden also tried heating a solution of 40-volume developer and water with a sous-vide circulator, which lightened the plastic without fully restoring it, and ozone with UV, which gave negligible or worse results.[2]
What goes wrong
[edit | edit source]- Streaks and blotches. They were still visible on the Dreamcast case ten years after treatment, and Farquhar reports that a second round of peroxide usually does not even out a blotchy result.[2][10]
- Yellowing returns. On the Dreamcast the treated plastic ended up more yellow than the untreated plastic.[2]
- Brittle plastic. In laboratory UVA ageing, the yellowing of ABS came with embrittlement of the exposed surface and a large loss of impact strength, so a yellowed part is likely to be weaker than new.[5] Farquhar considers that chemical treatment makes plastic more brittle still, while a week of sunlight did not seem to.[10]
Before treating
[edit | edit source]- Compare the yellowed surface with an area that was covered, such as the plastic under a label or badge, which keeps the original colour.[10]
- Clean the part and compare again.
- Decide whether to treat at all. The treatment cannot be undone, and in the one ten-year comparison the untreated plastic aged better.[2]
Related pages
[edit | edit source]References
[edit | edit source]- ↑ 1.0 1.1 Cory Doctorow, Open source computer polish: Retr0Brite, 2 March 2009—link(accessed 2026-10-01) Quotes Dave Stevenson: the method was "finally cracked in late July 2008 with a mixture of hydrogen peroxide, a small amount of an 'Oxy' laundry booster as a catalyst and a UV lamp", demonstrated on the English Amiga Board; TAED is "the booster in the 'active oxygen' laundry products".
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Jowi Morales, A 10-year study indicates that treated surfaces turn yellow more severely than untreated plastic parts – retrobrighting does more harm than good to consoles, 6 December 2025—link(accessed 2026-10-01) Reports Jueden's video: peroxide and sunlight on the top and bottom cases (not the lid) in 2015; streaking and blotching; the treated part of the underside more yellow than the part covered by tape; a sous-vide method with Salon Care 40 Volume Clear Developer that did not fully restore the colour; ozone and UV experiments with negligible or worse results.
- ↑ 3.0 3.1 Damien McFerran, 'Retrobrighting' Might Actually Cause More Harm Than Good To Your Yellowing Consoles, 8 December 2025—link(accessed 2026-10-01)
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Carl Roth GmbH + Co. KG, Safety data sheet: Hydrogen peroxide 50 % technical, stabilized, article 0034, GB version 8.0, revised 20 March 2026, SDB-0034-GB-EN—link(accessed 2026-10-01) Section 3 gives the GB CLP harmonised entry (index 008-003-00-9) with its specific concentration limits: Ox. Liq. 1 H271 C ≥ 70 %; Ox. Liq. 2 H272 50 % ≤ C < 70 %; Skin Corr. 1A H314 C ≥ 70 %; Skin Corr. 1B H314 50 % ≤ C < 70 %; Skin Irrit. 2 H315 35 % ≤ C < 50 %; Eye Dam. 1 H318 C ≥ 8 %; Eye Irrit. 2 H319 5 % ≤ C < 8 %; STOT SE 3 H335 C ≥ 35 %. Section 4: flush eyes with flowing water for 10 to 15 minutes and see an ophthalmologist. Section 7: keep in the original container, protect from sunlight, do not keep the container sealed. Section 10: violent reaction with acetone, alcohols, alkalis, ammonia, metals and reducing agents among others; incompatible with lead, iron, copper, bronze, brass, silver, zinc and chromium.
- ↑ 5.0 5.1 Rudinei Fiorio, Sara Villanueva, Alberto Sánchez, Dagmar R. D'hooge and Ludwig Cardon, "Influence of Different Stabilization Systems and Multiple Ultraviolet A (UVA) Aging/Recycling Steps on Physicochemical, Mechanical, Colorimetric, and Thermal-Oxidative Properties of ABS", Materials 13 (1), 212 (2020), doi:10.3390/ma13010212, open access (PMC6981387). Introduction: in polybutadiene-containing polymers such as ABS "the PB phase is initially degraded, reducing the elastomeric properties of the rubbery phase and inducing discoloration and losses in impact strength". Abstract and section 3.4: UVA aging "promotes degradation and embrittlement of the surface exposed to radiation" and increases the yellowing index; "Photo-oxidation of ABS increases the UV and visible light absorption, increasing the yellowing".
- ↑ 6.0 6.1 Regulation (EC) No 1223/2009 on cosmetic products, Annex III, entry 12 (hydrogen peroxide and compounds that release it), as adopted, Annex III—link(accessed 2026-10-01) Hair products: "12 % H2O2 (40 volumes), present or released"; label warnings "Wear suitable gloves", "Contains hydrogen peroxide", "Avoid contact with eyes", "Rinse eyes immediately if product comes into contact with them".
- ↑ 7.0 7.1 Evan Narcisse, The Secret To Keeping Old Consoles Looking New? Hair Product., 24 September 2014—link(accessed 2026-10-01) Hydrogen peroxide developer crème, gloves, repeated coats and a few hours of bright sunlight on a PlayStation and Sega Saturn.
- ↑ Jason Fitzpatrick, Retr0Bright Restores Yellowed Vintage Plastic to Factory Fresh, 7 March 2009—link(accessed 2026-10-01)
- ↑ Terry Stewart, De-yellowing computers with laundry whiteners (i.e. sodium percarbonate) only, 21 January 2011—link(accessed 2026-10-01)
- ↑ 10.0 10.1 10.2 10.3 Dave Farquhar, Retrobright with sunlight and no chemicals, 22 June 2020—link(accessed 2026-10-01)