⚠️ No technique is foolproof: You may destroy the disk in the process of cleaning it!

⚠️ THIS PAGE IS A WORK IN PROGRESS!!

This page gathers information from the #cleaning-tips forum on the applesaucefdc Discord. If you have questions, that is the best place to ask.

The purpose of cleaning a floppy disk is to remove any surface build-up while leaving the magnetic medium intact. This can be more complicated than one might expect.

8“ and 5¼” floppies consist of a plastic disk coated with a magnetic medium (sometimes called the cookie). The disk has a large hole in the center, sometimes reinforced with a plastic or metal ring. The disk is sandwiched between two layers of non-woven, anti-static fabric called the liner. These are enclosed in a square plastic cover (usually PVC) with several holes cut out called the jacket.

The plastic disk and the magnetic medium are the heart of the floppy disk as they hold the data. The plastic disk is a thin sheet of mylar about 0.07 mm (70 μm) thick. The magnetic coating on the plastic disk is even thinner. For example, it is 2.794 μm (micrometers) thick for a high-density 8“ floppy—about the length of an e. coli bacterium. It consists of magnetic powder (iron oxide) and a binder. Unfortunately, the formulation of the binder by different manufacturers in unknown. One patent lists the binder as “polyester polyurethane”.¹⁾

The liner ensures that the plastic disk spins freely. It also collects dust and debris that find their way into the jacket. The liner can be made out of several kinds of fibers. It is imbued with an anti-static treatment which helps it attract and hold onto dust. It is usually physically bonded to the jacket.

The jacket protects the disk from rough handling and helps it maintain its shape.

3½” floppies are similar to 8“ and 5¼” floppies in their major components, but differ in the details. 3½“ floppies have a similar mylar disk coated with a magnetic medium, but the reinforcement ring is replaced with a stainless steel hub. The hub is attached to the disk with a ring of adhesive. The disk is still sandwiched between two sheets of fabric liner. The disk and liner are enclosed in a shell of plastic. Attached to the shell is a spring-loaded shutter that protects the media that is be exposed through the head access slot in the shell.

The liner of 3½” floppies is similar to the liner of 8“ and 5¼” floppies and serves the same purpose. One major difference is that it is not glued to the shell. It is held close to the disk with wiper tabs or lifters, which are small bent pieces of flexible plastic adhered to the shell. The wiper tabs keep the liner close to the disk to clean it as it spins.

The shutter is made out of stainless steel. It is held closed by a spring. When a disk is inserted into a drive, the shutter is gently pushed out of the way to expose the magnetic medium to the drive heads.

Floppy disks can have several problems.

Some of the substances that can build up on disk surfaces are:

• dust: disks left out of their sleeves can accumulate dust in the window
• dirt and grime: in harsh environments, dirt and grime can accumulate on the disk surface during use
• tar: if the disk has been used in a room with a smoker, tar can accumulate on the surface
• mold: some molds can grow on the disk in certain temperatures and humidities

These contaminants can attack the disk in multiple ways and their effects vary depending on how much build-up there is.

One of the biggest problems with disks that have a lot of build-up is that not only is the disk surface contaminated, but the liner is, too. In this case, merely spinning the disk in the drive can wear away the magnetic media, resulting permanent data loss.

With time or the over-use of solvents, the binder can break down causing the magnetic oxide layer to flake away, resulting in permanent data loss. Trying to clean a disk with weak binder will probably destroy it.

Over time, the glue holding the reinforcement ring to the disk may degrade, causing the ring to separate from the disk. This is usually recoverable for 5¼“ disks if the ring doesn't rip the disk. For 3½” floppies, this is usually fatal as it is next to impossible to correctly center the hub.

Before trying to clean a disk, one needs to ask, “What is the most important thing about this disk?”

If the answer is that the data on the disk is the most important thing, then, depending on how dirty it is, the best course of action may be to disassemble the disk, clean it, then mount it in a new jacket with a clean liner.

If the answer is that keeping the disk physically intact is the most important thing, then you may not want to even try cleaning it.

There are several schools of thought on the best solvents to clean disks that roughly break down into two camps:

• water: only use water, a little detergent, and a surfactant
• alcohol: use isopropyl alcohol

This section tries to explore the pros and cons of each.

TODO(flan): cyclomethicone TODO(flan): baking

Water is gentler on the magnetic media than other solvents. When disks are affected by mold, water is often sufficient to clean the media.

TODO(flan): Example detergents and surfactants

The biggest problem with alcohol is that it can dissolve the binder that the oxide is suspended in. From @bitsavers:

When in doubt, look at the surface under magnification. If you do that with an alcohol based cleaner, you will never use it again.

7jp4-guy said:

OK. So I just did something that I am not sure if I should regret or not. I am working on a lot of LOAD'N'GO! disks for Apple II which are unpreserved and are badly damaged with mildew. I have tried cleaning the disks in the jacket using alcohol and repeatedly reading them. This has not been very successful to say the least. I ended up damaging the media in Frogger (one of the ones that is previously preserved so I did it first.) Next up was MAGIC MOVER which I don't think is preserved. After some thought, I decided to take a big risk and to damage it a bit in the hopes of saving the data. What I did was slit open the jacket, remove the media itself, wash it in water and then place it in a new jacket. The results were absolutely astonishing - both sides of the disk read on the first try without error.

But this came at the cost of damaging the jacket, which is fine if you are really after the data. As david.rysk said:

Preserving the data is more important than the jacket, after all the physical artifact is kinda useless without the data.

The flip side is that if the disk has been imaged, keeping the physical artifact intact might be preferable without trying to read the data (because that may destroy it).

Here is a list of brands that people have reported as particularly difficult or bad:

• Riaz, R. Floppy disk. How Products Are Made. Retrieved November 23, 2022, from http://www.madehow.com/Volume-1/Floppy-Disk.html
• PC Magazine. Definition of floppy disk. PCMAG. Retrieved November 23, 2022, from https://www.pcmag.com/encyclopedia/term/floppy-disk
• Masakazu Hoshino, Eizou Sakurai, Hajime Itoh, Kunio Iwase, Toshio Nagasaka (1999). U.S. Patent No. 5,955,169. Washington, DC: U.S. Patent and Trademark Office. Retrieved November 23, 2022, from https://patents.google.com/patent/US5955169A/en.