Tag: yellowing

Retr0bright – What’s that then?

It’s a process used to restore old Yellowed plastic back to its original state. Or at least it’s a way to try to. Read on and I’ll explain.

(Here is my understanding of the ABS plastic Yellowing process. There may be slight inaccuracies for which i apologise. Please do your own research on the subject. Further enquiries may be needed to satisfy your curious minds!)

Anyone who has any dealings with items built in the 80s/90s such as me will have come across an issue, especially related to anything built with ABS Plastic, and that would be the common phenomena of “Yellowing”.

If you own a game console or toy with white ABS there is the good chance that all or at least some of it will have turned a shade of yellow,

ABS plastic – otherwise technically known by its scientific name of “Acrylonitrile butadiene styrene” is a thermoplastic polymer. This means that it becomes pliable at an elevated temperature and solidifies on cooling. ABS was a flame retardant material that was regularly used as a casing for computers, gaming consoles and similar items just in case they were to overheat and catch fire. It was also used in Lego bricks for some reason, god knows how these were meant to catch fire though!

The yellowing issue lay with a chemical used in the manufacturing process called Bromine. When exposed to UV light or excessive heat this caused the photo oxidation of polymers within the chemical to break polymer chains causing the plastic to yellow and become brittle.

Come on then, tell us what retrobrighting is..

Retrobright or retr0brite as it is stylised by the guys who discovered the process, is an approach to removing yellowing from these ABS plastics, a kind of bleaching process if you like. The original recipe for Rerobright was discovered purely by chance by the CBM Museum at Wuppertal in Germany in March of 2008. I’m not going to go into the finite detail in this post, however you can read all about it here at the original Retr0brite project site: The Retr0brite Project.

The process can be a little hit and miss, however there are a lot of documented cases of it working very well. There is a downside that the yellowing can overtime return, as this process only really whitens the surface problem whilst those old polymers are still breaking down deep inside the plastic where this treatment doesn’t reach.

Before and after effects of this process. Pictures copyright The Retr0bight project

The process

I’m only going to touch on the process here, there are many other detailed explanations available on line, that explain the process far better than i could, here is one for example from the “How to Geek” site. How to clean old yellowed plastic on retro computers and game systems.

I will explain the process briefly below, but in no way do i accept responsibility for the way you approach the process. That is down to you entirely and i suggest you read up deeply on the subject prior to attempting this process. You have been warned!

What you need

  • The offending piece of plastic
  • Clingfilm
  • Paint brush or suitable application brush
  • Protective gloves
  • Eye protection
  • 40 volume oxidising cream (Hydrogen peroxide, salon hairdresser strength.
  • Sunshine (Hard to find here in the UK) or a UV lamp

For starters make sure the item you want to brighten is clean. Make sure you have eye protection and gloves on as the peroxide can cause skin burns and the last place you want it is in your eyes, believe me.

Lay down some cling film. Place your subject matter on the clingfilm. Apply some cream onto the object you want to lighten and smear it around ensuring the whole item is covered in the peroxide solution, failure to do this can cause blushing and streaking. When you are happy that the subject matter is fully treated, cover the whole item in the clingfilm ensuring there are no holes where the solution can evaporate from.

Next place the item where the whitening can take place. Out in direct sunlight and leave it there for the entire day. Indoors a UV light lamp can also be used. The UV rays that originally caused the yellowing will now react with the Peroxide to reverse the process. This does take time though and in some cases where the yellowing is particularly bad a second or third treatment may be required.

Remove the clingfilm after a sufficient UV exposure and ensure the subject matter is washed thoroughly to remove all traces of the peroxide developer. Again, ensure you have gloves on until all traces of the chemical are removed.

Dry the subject matter or allow it to dry naturally. Hey presto! Job done. And thats basically it.

I’ve covered this subject, as it is something i will be attempting over the coming months. I will address the process in individual posts relative to the item i will be working on at the time.

Thanks for passing by, it’s always appreciated.

Samsung SQ3000 electronic typewriter – assessment & repair

This is the follow up to a recently obtained electronic typewriter that was purchased in January 2025, the initial post can be found here: Samsung SQ3000 electronic typewriter.

Samsung SQ3000 electronic typewriter

The following post will deal with the assessment on its arrival and what I am going to try to do, to get it back working again, as close as possible to its original state.

I’ve downloaded an instruction I manual, I’ve had to download one for a Smith Corona Wordsmith 200, it is in theory the exact same unit, just under a different manufacturers branding.

Assessment

It’s arrived and apart from a little age yellowing it looks ok. There is a PAT testing sticker that says it was last electrically tested back in 1998 and is due a retest in 1999. This corresponds with my date estimate of mid 90s.

Yellowing
Pat test date

I will retest and renew the safety checks when I’m finished working on it. I have noticed that the paper bail/release rail is broken on the left hand side so I will have to add that to the repairs, this shouldn’t be a major concern.

Paper bail snapped
Broken piece recovered

Before I took the roller out to get to the paper bail I did start the machine up. Everything went as expected and when I tried to type I was getting some weird reactions to the keys I was pushing. All kinds of characters were appearing.

Before

I checked the daisy wheel and there was a click. It wasn’t sitting right. I reset the machine using the two reset buttons and the machine then went through its reset programme, pretty much the same effect as turning it off and on again. (Not much changes in the way of tech there then)

After

Well that’s worked fine, I have tried every combination on the keyboard including the erase function and this is now fully working. It really was quite simple. My next job is to try and fix this paper bail.

Paper bail removed for fixing

There is quite a bit of dust and dirt inside that needs removing. And whilst I’m at it I will lightly re grease the areas that need it. Let’s be honest it’s not been done in the last 30yrs so now is as good a time as any. Inside will get a light hoovering and a bit of a tart up, I’m not going to go mad. I will clean the outside and all knobs and buttons and try to get rid of some of the yellowing, but to be honest as long as it’s clean I’m not too worried about age marks.

Roller dirt
Grease needs replacing
Roller platten dirt

The keyboard has lost a few of its letters. I will remove what is left of some of them and use some keyboard decals to replace the missing ones. This will be one of the last jobs I do.

Characters missing
Keyboard

Well that’s the assessment done and apart from a few small issues and requiring some basic maintenance I don’t think we have an immense amount of work to carry out. We know it now works. Let’s hope I don’t cause any further carnage whilst working on it.

Let’s get to work.

Repair

Right it’s straight onto the paper bail to try and fix the snapped end. Firstly I’m just going to use some superglue to get it in place. When this is dry I’m going to create two “Doublers”, place one either side of the damaged part and glue these in place to create a stronger repair and to add some stability to this area.

I’ve got some black semi rigid plastic. I’ve created a small template from a tracing that I did of the good right hand side of the bail.

Plastic
Template

I now have two doublers cut from the plastic that I will use as explained above.

Two doublers

It doesn’t matter that they are not perfectly shaped, however they both fit perfectly well into the profile of the bail arm, and this portion of the arm is hidden in the typewriter housing anyway, so the part will not be visible, but it will now be strong.

Superglued
Doublers in place and clamped

The Doublers have been put in place using a quick set epoxy resin, I will leave this to dry for a good few hours before I tidy it up, with a light clean, and then I will try to get it back in place.

Bail arm repaired, installed and working.

Now that’s done i’ve gone inside and there were a nice couple of spider webs around the transformer that are now history. I’ve secured the cable in the rear of the unit that never had any tension restraint, so that there will be no issues, should anyone now give a good yank on the cable lead. This is a safety addition I have made that was never on the original unit.

Cable restraint screwed to base to prevent strain on internal wires in and around the transformer bay.

I have also tightened all screws and checked the wiring and this all seems ok. Plug and fuse have been checked and all is looking good. I’ll carry out a PAT test once I’ve finished the clean up.

Roller cleaned and degreased
Platten switch cleaned

I’ve cleaned the main roller with alcohol, and removed all the old grease and dirt from the platten adjuster switch and the roller advance knob. I have removed the platten plate as well as the six mini rollers that are here. I’ve cleaned them all and re assembled/installed them.

Platten plate
Platten roller
Rollers installed and platten complete

I have cleaned the daisy wheel as well as in and around the printing head unit.

Clean inside
Degreased

Inside the unit I have given a good hoover as well as a light clean and again removed more old grease. I have given the exterior plastic a preliminary polish, this has removed some of the yellowing and made it look “cleaner” I am not going to worry too much about the yellowing as it isn’t that bad, and I don’t really want to venture into carrying out a “Retrobrite” on this unit. It would take too long and there would be no benefit for this project.

I’ve now added very small amounts of a watch lubricant to those areas that i have previously cleaned and removed the old grease from.

Light lubricant
Main transport lightly lubricated

The unit has been reassembled and I’m pleased to say it is still working fine. It’s running smoothly and all aspects of the unit seem to be working just fine. To be honest it seems to be printing clearer to me.

Daisy wheel and print quality is perfect

I don’t know how long the print cartridge has been installed but I suspect it may have been a few years back. It’s almost finished, and I do have a replacement on order. I’m sure a fresh cartridge will make the print stand out even more.

Next I’m going to have a go at replacing some, or even all of the keyboard letters. It all depends how it looks when I start replacing them. I’m going to gently rub off the lettering that is left and clean the keys using a 95% pure Isopropyl alcohol solution (IPA).

All damaged and missing key decals removed in preparation for replacement new decals. Others may have to be removed dependant on how the new ones look when in place.

These are the replacement key decals I will be attempting to use.

Qwerty keyboard decals

I’ve replaced the damaged key decals. The ones I’ve used are a lot brighter than the original ones and really accentuate the yellowing. I’m not troubled by this as it keeps its “Old” look. I would have to scrape and wipe for hours to remove all the other keys and to be honest it would look just like someone had gone abroad to have a bright white set of dodgy veneers installed, it would look quite out of place, and in your face. Just like a Cheshire Cat smile.

New veneers anyone?

It serves a purpose and just allows the unit to be usable again.

The final product:

Looking damned fine if I say so myself

Fortunately a lot of the equipment and parts I have used, I was already in possession of, so there are no additional costs for this project. Below you can view the total costings for this project as they currently stand:

  • Purchase inc postage £13.14
  • Cable restraint £0.25
  • Keyboard decals £1.25
  • Total cost of project £14.64

Again I have managed to save a fantastic 90s retro item from landfill for very little cost, and that is a fantastic result. It has years of use left in it, as long as the consumables remain available, and of that I am confident that they will be available, for at least the next few years. The unit is clean, I’ve just carried out an electrical PAT test and it is electrically sound.

Believe it or not I’m going to go back in time and will write some traditional typewritten letters to friends and family. I’m looking forward to doing that and it will certainly surprise them, it will be totally unexpected.

When all that is done, i will donate this unit to our local LOROS Hospice shop so they can sell it on and raise much needed funds. They deserve it. Edit: This was done in March 2025 at their shop in Hamilton Leicester. I hope it gets them a good price.

Watch the brief video for the final words on this restoration. All 13 seconds of it.

And that’s it folks..

Thanks for passing by.