Clean Flange

Before you re-install the tower, both the upper and bottom IVC flanges need to be cleaned. The method to clean both surfaces is the same. The items you will require to do so are a plastic scraper, scotch brite pads, isopropanol or methanol, a wooden cotton swab and clean room wipes. For scraps of indium that you remove, you can place them in the indium recycle bottle. When cleaning the flanges, there are three surfaces that you need to make sure are absolutely free of indium and other residue (see images). Note of caution: always be careful when using a solvent - sometimes it can splash back when sprayed. Thus, it is important to wear goggles for protection. Please note where the eye wash is in case of emergency. You should know how to use this already. The cleaning process for the flanges takes several iterations (and patience). The goal is to remove all residue but rushing this or applying too much pressure inappropriately could result in scratching the flange, which is far worse than a dirty flange.

1. Press the edge of the scraper against the flange to remove as much indium as possible.
2. Spray a small square of scotch brite with isopropanol and rub it against the flange surface. Never use the plastic scraper with the scotch brite to scrape against the flange surface.
3. Spray a clean room wipe with solvent and wipe the surface to remove the residue left by the scotch brite.
4. Inspect the surface. Can you see any indium? Depending on the amount of vacuum grease that was used to prepare this seal, there may be quite a bit of indium left after the first round of scraping. If there is still visible indium left, use the scraper again to try to scrape it off (the scotch brite will have helped to make this easier).
5. Re-scrub the flange surface using the scotch brite, and wipe it clean afterwards with an solvent-soaked cloth.
6. Once you can no longer see ANY silver specks, you will now work to clean off all residue undetectable to the naked eye.
7. Spray a clean wipe with solvent, fold it over the plastic scraper, press the wipe against the flange surface. Do this over ALL surfaces, and make sure that you adjust the wipe so you’re not rubbing a soiled part of the wipe back on to the flange surface. Take a look at the wipe and see if you can find any indium on it. It’s surprising to note the amount of indium left on the surface that isn’t visible to the eye!
8. Using the same method of wrapping the plastic scraper in the solvent-soaked wipe, clean the edges of the screw holes since indium is bound to have been rubbed / spread onto there.
9. Clean the inside of the screw holes. They don’t have to be immaculate, but debris does get in there. You can use an solvent-soaked wipe and wrap it around the end of the wooden cotton swab in order to clean inside the holes. For each screw hole you can shift to a different part of the wipe to wrap around the swab (this spares us from having to use multiple cotton swabs).
10. Again, go back around the surfaces of the flange with the scraper wrapped in the wipe, and keep doing so until no residue shows on the wipe anymore. Make sure as well that threads from the wipe aren’t being left on the flange surface.
11. Get a second opinion to confirm that you’ve successfully cleaned the flange.