Casio BP-100 (White) – Restoration

One day, while checking Polish classifieds sites, I came across a BP-100 in white. I really like this version, and it does not show up often. Sometimes you can find one on eBay, but the white ones are usually priced quite high.

This time I got lucky. The watch belonged to a Polish collector who had kept it in a drawer for years. I negotiated the price by promising a quick purchase, and a few days later the watch landed on my workbench. It looked exactly like the photos and the description: visual condition was great, no scratches anywhere on the case. 👍

The BP-100 is one of those Casio oddities that make this hobby fun. It comes with a built-in blood pressure and heart rate sensor, which felt like pure 90s sci-fi when it launched. Finding one in this condition, in white, was a nice surprise, even if it came with one classic problem I would need to fix.

What Did the Watch Look Like When It Arrived?

Overall, the case was in great shape. No scratches, no cracks, nothing that would need heavy repair work. Exactly as the seller described.

The original strap was a different story. The rubber had lost all its properties over the years and simply fell apart. This is very common on old Casio straps, the resin dries out and cracks with age, no matter how carefully the watch was stored.

The bigger issue was the color. This BP-100 was originally white, but years of sun exposure had turned the case a dull cream color. This is a well known problem with white Casio watches. The white resin yellows over time, and it does not go back on its own. I already had a method for this, so I knew this was the main job ahead of me. 😅

Casio BP-100 (White) – Restoration Process

Step 1: Solving the Strap Problem

The original strap for the BP-100 is not cheap to find, and the white version is even harder to get and more expensive. Instead of hunting down a dedicated replacement, I decided to get creative.

I matched a strap from a Casio SDB-500, which fit the lug width perfectly. The only issue was the clasp. I wanted to keep the original white buckle with the Casio branding on it, since that little detail makes the watch feel authentic. To get it off the dead strap, I used pliers and warmed it up with a hairdryer. The heat loosened the material enough that the clasp popped open without cracking. From there, it was just a matter of sliding it onto the new SDB-500 strap. Dimensionally, it matched up without any modification needed.

Step 2: Prepping the Case for Whitening

Before any bleaching could happen, I had to strip the case down completely. All buttons and colored plastic parts needed to come off, since the whitening method only works properly on plain white or gray plastic.

This model has a tricky detail on the front: a plastic panel in a different color (blue, in this case) sitting right on the front of the case. Unlike most parts on this watch, this panel is not held in with snaps or clips, it is glued directly to the case. If I bleached the case with the panel still attached, the blue plastic would have picked up the oxidant and been ruined.

To get it off safely, I used a hairdryer to warm the glue, then worked a thin tool gently under the edge of the panel until it released fully. After that, I scraped off the old adhesive residue and cleaned the surface underneath, getting it ready for both bleaching and, later, reattachment.

Step 3: The Whitening Process

This is the method I always use for yellowed white or gray Casio cases, and it works well when done carefully. First, the case needs to be fully disassembled, no buttons, no colored inserts, nothing left that could react badly with the chemical.

I coated the case in 12% oxidant, the same kind used for hair bleaching, then wrapped it tightly in foil and set it out in direct sunlight. It is important to know this method only works on white or gray cases. I have tested it on other colors before on cheap Casio cases, and instead of restoring the original shade, it ruins the color permanently. One thing that always surprises people: the oxidant does not fade printed text or engraved markings on the case, so there is no risk of losing the branding or model details.

One safety note worth repeating: the oxidant is corrosive to skin, so gloves are a must throughout the whole process.

After about 1.5 days sitting in the sun, the transformation was clear. The case went from a dull, creamy yellow back to a proper bright white. Every time I do this, it still feels a little bit like magic. 🛠️

Step 4: Reassembly

With the case white again, it was time to put everything back together. For the front panel, I used 3M double-sided tape, a brand I trust because it holds well long term and does not lift over time. I applied it across almost the entire surface under the panel, then pressed it down firmly and held it in place for a good while to make sure the bond was solid.

After that, I reinstalled the buttons, the module, and the gasket, adding a bit of silicone grease for a proper seal. I also fitted new springs for the buzzer and the BP sensor, since these small parts wear out over time and are worth replacing during any full restoration like this.

Step 5: Polishing the Back Cover

Last step on the case itself was the stainless steel back cover. I polished it and restored the original one-directional brushed finish, so it looks factory fresh rather than scuffed up from decades of wear.

With the strap on, the panel back in place, and the module sealed up, the BP-100 was finally whole again.

Final Result

With the new strap on, the panel back in place, and the case bright white again, the BP-100 looked like a completely different watch compared to the cream colored piece that arrived on my bench. The white clasp with the Casio branding ties everything together nicely, so even with a donor strap from an SDB-500, it still feels original to this model.

I will be honest, I am more of a mechanic than a strict collector. I care more about getting a watch working and looking right than chasing rare pieces for the sake of it. But this one is different. This white BP-100 has become one of my favorites, and it is staying in my personal collection. This one is not going up for sale. 👍

Have you ever run into a yellowed white Casio in your own collection? Or tried bleaching a case back to its original color yourself? Let me know in the comments, I would love to hear how it went.

Want Your Vintage Casio Restored?

This Casio BP-100 (White) is one example of the restorations I do. I restore vintage Casio watches for collectors and enthusiasts around the world, everything from straightforward cleanups to more complex repairs like whitening a yellowed resin case and swapping in a donor strap when the original is too rare or too expensive to find.

You can see more of my previous projects here: 👉 casiorestore.com/projects-restorations

I work mainly with collectors across Europe and shipping is not a problem. I have already completed restorations for collectors from the UK, Scotland, Sweden, Ireland, Spain, France, and more. That said, sometimes logistics from outside Europe can be worked out too, it just takes a bit of creativity. 😄 Every project is discussed individually, so we always agree on the scope and price before starting. 🛠️

The process is simple:

• Write to me on Instagram: @vintage.casio.restore
• Or send me an email: vintagecasiorestore@gmail.com
• Describe the problem with your watch, send clear photos, and tell me your country.

If your vintage Casio deserves a second life, I will be happy to help. 👍