HP-35 cleanning

[Josef]

I recently tried the calculator in the complete package, but it was pretty dirty and scuffed the top silver framing. I cleaned the calculator and repaired the framing with a silver marker.

   

   

   

[Jeff_Birt]

That looks nice.

[teenix]

Good job, it looks great.

I have touched up some Classics using the same method as well. I usually clean the casing with a soft cloth lightly soaked with warm soapy water, followed by plain warm water. When dry, I use tape to mask any black plastic areas that the pen tip might accidently touch. I then lightly scuff the silver area with a small piece of very fine grit emery paper. Light application doesn't damage the plastic and can help remove any tiny ridges where the original silver may have peeled off. It also gives a dull surface for the new paint to adhere to. This is followed by a quick wipe of the prepared surface with a dry soft cloth with just a hint of isopropyl alcohol on it.

I have found that to get the best results, you should prepare yourself to draw one continuous line on the surface that is being touched up. If you try to stop and start drawing small lines across the surface, the paint is applied unevenly and can give a messy blobby appearance. The paint pen nib is wide enough to retouch the sides and bottom areas in one pass, and maybe two passes are required for the wider top bar under the display.

Sometimes a repeat is required after drying as any originally exposed black plastic areas might still show through.

The paint is not as hardy as the original silver coating, but it still creates a nice appearance.

cheers

Tony

[rprosperi]

Nice suggestion to use emery paper to roughen the surface, thanks Tony. Other than that I do it the exact same way and am always pleased with how good the results are. From now on, I'll be using the emery paper as well.

Thanks!

[teenix]

(08-27-2023 11:16 PM)rprosperi Wrote:  Nice suggestion to use emery paper to roughen the surface, thanks Tony. Other than that I do it the exact same way and am always pleased with how good the results are. From now on, I'll be using the emery paper as well.

Thanks!

Thanks Bob, I use really fine paper, 2400 upwards, almost talcum powder grit to avoid deep scratches, and pieces just large enough to handle to help avoiding accidently rubbing it on other parts. The plastic is reasonably soft, so light finger pressure works well and helps avoid creating furrows if you pressed too hard.

The old silver does not need to be rubbed off, it is just the overall scuffing that helps.

cheers

Tony

[John Garza (3665)]

All good advice. I've also found it best to remove/clean all silver and repaint everything. The silver colors are sometimes not an exact match or there is some discoloration (stains?) that happens to the old silver over the years. When dry, I apply an enamel clearcoat over the new silver. This helps prevent it rubbing off and gives the color some depth. It looks more like the original metal bar than paint.

-J

[Josef]

I first clean the old silver layer and then apply a new coat to the damaged area. I try to leave as much of the original look and materials as possible. The new paint looks identical to the old.

[aurelio]

(08-27-2023 08:39 PM)teenix Wrote:  Good job, it looks great.

I have touched up some Classics using the same method as well. I usually clean the casing with a soft cloth lightly soaked with warm soapy water, followed by plain warm water. When dry, I use tape to mask any black plastic areas that the pen tip might accidently touch. I then lightly scuff the silver area with a small piece of very fine grit emery paper. Light application doesn't damage the plastic and can help remove any tiny ridges where the original silver may have peeled off. It also gives a dull surface for the new paint to adhere to. This is followed by a quick wipe of the prepared surface with a dry soft cloth with just a hint of isopropyl alcohol on it.

I have found that to get the best results, you should prepare yourself to draw one continuous line on the surface that is being touched up. If you try to stop and start drawing small lines across the surface, the paint is applied unevenly and can give a messy blobby appearance. The paint pen nib is wide enough to retouch the sides and bottom areas in one pass, and maybe two passes are required for the wider top bar under the display.


Sometimes a repeat is required after drying as any originally exposed black plastic areas might still show through.

The paint is not as hardy as the original silver coating, but it still creates a nice appearance.

cheers

Tony

Thank-you Tony, thank you for sharing your experience and advices, I did exactly as you described when retouching the silver: you focused exactly the most difficult step, and to retouching the sides and bottom areas in one pass is always quite a challenge
I don't know how and if it is really possible to restore the yellowed keyes...

Compliments Josef for your job!!!!

[Josef]

Thank you! As for the yellowed calculator keys, I'd like to try this.

https://www.youtube.com/watch?v=DzINMDesx-M

[vaklaff]

(09-04-2023 06:20 AM)Josef Wrote:  Thank you! As for the yellowed calculator keys, I'd like to try this.

https://www.youtube.com/watch?v=DzINMDesx-M

No personal experience but I'd suggest caution. The video's author mentions that he tried to brighten the keys too but their color started to become uneven so he stopped. Maybe because it's hard to keep many little objects in "even" positions? The material plays role as well.

I believe you speak Czech so you may want to read:
https://blog.root.cz/retro-pocitace-hrdi...brighting/
https://www.root.cz/clanky/projekt-retrobrighting/
https://www.root.cz/clanky/retrobrightin...n-prusvih/
Not written by me, I'm just keeping them around - in case I muster my courage :-)

If you play with retrobrighting please share your experience whatever the results are!

[BruceH]

(08-27-2023 08:39 PM)teenix Wrote:  a soft cloth lightly soaked with warm soapy water

:-)

[Jeff_Birt]

(09-04-2023 10:57 AM)vaklaff Wrote:  No personal experience but I'd suggest caution. The video's author mentions that he tried to brighten the keys too but their color started to become uneven so he stopped. Maybe because it's hard to keep many little objects in "even" positions? The material plays role as well.

If you play with retrobrighting please share your experience whatever the results are!

I did a large amount of research into the Retr0Brite process a few years ago which was documented in the first below video and the paper which is in the video description. The short story is that not every type of plastic responds well but most lighter colors do.

The second two videos are a VIC-20 I restored going to extremes to see if the Retr0Brite process 'destroys' plastic. Some of the brown keys were very faded and they can turn blotchy when you try to Retr0Brite them. Instead, I polished them since they are double-shot injected keys. This is shown in the second video. Of course, you can't do this with keys that are painted.

https://youtu.be/YPl356YKcVs

https://youtu.be/YPl356YKcVs

https://youtu.be/_IuGFQ6-GAA

[vaklaff]

Thanks Jeff! Extraordinary stuff, plenty of work behind it.

[Josef]

(09-04-2023 10:57 AM)vaklaff Wrote:  No personal experience but I'd suggest caution. The video's author mentions that he tried to brighten the keys too but their color started to become uneven so he stopped. Maybe because it's hard to keep many little objects in "even" positions? The material plays role as well.

I believe you speak Czech so you may want to read:
https://blog.root.cz/retro-pocitace-hrdi...brighting/
https://www.root.cz/clanky/projekt-retrobrighting/
https://www.root.cz/clanky/retrobrightin...n-prusvih/
Not written by me, I'm just keeping them around - in case I muster my courage :-)

If you play with retrobrighting please share your experience whatever the results are!

Thanks for the links, I'll take a look at the experience and let you know how it turns out