The comp.sys.apple2 Usenet newsgroup Apple II FAQs originate from the II Computing Apple II site, 1997-2012. Csa2 FAQs resource file: R035WHITEN.TXT (also R035WHITEN.HTML) .... Using Hydrogen Peroxide to . 'Get the Yellow Out' from George Rentovich, the guys on the English Amiga Board, and Rubywand Years of exposure to sunlight and other UV can result in yellowing or even browning of Apple II cases. One solution is to pick a color and paint the case via a few light coats of a spray paint. If you want to restore the original color, you can get a good match using Apple II pictures available on the net. A recently discovered alternative to painting is bleaching out the discoloration using hydrogen peroxide (H2O2). According to claims, the process described here does not damage painted labels, metal inserts, etc. except as they may be attached by a water soluable adhesive. Note: Most of the info here comes from the English Amiga Board at http://eab.abime.net/showthread.php?t=37808 . What You Need - Hydrogen peroxide (H2O2)- water added as necessary to get desired concentration - An 'Oxy' cleaner such as Oxi Clean Versatile Stain Remover or Vanish Oxy Action or pure TAED (Tetra Acetyl Ethylene Diamine)-- don't need much - UV 'Blacklight' bulb (60 watts or so) in a lamp (indoors) or sunlight Note: Do not use other UV sources, such as germicidal lights. - Plastic or glass container (possibly with a transparent cover) - Bostik Blu-Tack or similar reusable adhesive to help hold small parts in position - Water close by, such as in a large bowl, for washup and washing off cleaned parts - Rubber gloves - Full protection goggles. You only get one pair of eyes! - Tongs may be helpful for retrieving smaller parts WARNING: Do Not even think about mixing in chlorine bleach with the H2O2! The result could be to release chlorine gas. Hydrogen Peroxide Mixture Hydrogen peroxide(H2O2) comes in two well-known forms: stable and unstable (rocket fuel) determined mainly by concentration. The highest concentration which is commonly available and which is allowed for postal shipping is 35%. H2O2 in useful strengths is available in various forms and concentrations from several sources including chemical sellers, cleaner makers, and hair product sellers. Sometimes H2O2 concentration is expressed in "volume". A peroxide product for hair bleaching may be labeled "40 Volume". To get the % concentration, you divide by 3.3. 40 Volume = about 12% H2O2. H2O2 specified as "not less than 20% nor more than 40%" is available in a gallon size as a cleaning product called "Urine Rescue" by Prochem for about $15/gallon. You can obtain 12% H2O2 (such as "Super Star 40 Volume Clear Peroxide Gallon" for $7.77/gallon) from various hair salon sellers. The higher the strength, the speedier the whitening. However, at 35% you have a more hazardous solution (e.g. in terms of skin/eye splashes) and will need to monitor the process more closely to avoid etching of the plastic. Another factor is that the H2O2 you use will probably not retain its whitening properties for more than a few days. If you use lower concentrations you can stretch out your H2O2 supply over more cleaning sessions. A good balance of speediness, hazards, and cost is around 20% H2O2. 12% is fine, too, but, slower. Whatever your concentration, you will need enough to keep the item being whitened wet during the process. Plain H2O2 is not particularly speedy as a whitener below roughly 100 degrees F. So, to activate the H2O2 a small amount of TAED (Tetra Acetyl Ethylene Diamine) is added at the start of the process. One popular cleaning product containing TAED is Oxi Clean. About 1/4 teaspoon per gallon of H2O2 solution is enough. Container This process requires UV light on the surfaces you wish to whiten. (This can come from the sun or a blacklight bulb.) Whatever container you use needs to keep the plastic part(s) in the solution and to allow light to reach the surfaces. Since the process does generate some heat it is best to avoid using exceptionally flimsy plastic containers. Some smaller parts may tend to float due to build up of gasses in gaps and recesses. A reusable adhesive gum, like Blu-Tack, can hold them in position in the tank so that keytops, etc. stay emersed in the solution and get light. The container, tank, etc. needs to be out of the reach of small children and pets. Be sure to let older children and anyone else who may be able to reach the container know that the stuff inside is not plain water and is hazardous. Place warning signs/notes on or near the container. If outside using sunlight, use a transparent lid or similar covering to keep out birds and insects. Some Hazards The main hazard from H2O2 is probably to eyes. Wear full protection goggles and have plain water available for flushing eyes or skin in case of contact with H2O2. Another hazard is the oxygen given off during the process. At higher concentrations oxygen can ignite from electrical sparks, candles, etc.. The place where you do the process should be well ventilated. The UV light to be used for indoor work is 'blacklight' UV. It is sometimes used to highlight posters in darkened rooms. (Other UV sources, such as various germicidal lights, can be more hazardous to vision.) It is best to avoid long exposures. Do not stare at the lighted process for extended periods. Process 1- Thorougly clean the item(s) to be whitened with soap and water. 2- Set the container for the cleaning process in a safe area out of reach of small children and pets. 3- Place the item(s) in the container. If KB keys or similar small items are to be cleaned, you may want to stick them in place with Blu-Tack, etc.. 4- Put on goggles and gloves. 5- Pour in the H2O2. Add water to get desired concentration. Do not fill to brim. Allow some room for foaming activity. 6- Add 1/4 teaspoon of an 'Oxy' cleaner or pure TAED per gallon of H2O2 solution. (Expect some foaming action.) 7- If indoors, turn On your blacklight(s). Check that surfaces to be whitened are getting light. 8- Every hour or so check the progress of the whitening. Time required depends upon many variables. It may be a few hours, several hours, or a few days. 9- When whitness is satisfactory, remove the part(s). Wash or submerge in plain water and dry. The Gel Option! In order to simplify whitening larger items such as cases, the EAB guys have developed an H2O2 gel which can be brushed on. Here's a quickie summary from a posting by Merlin ... Ingredients 1 pint Hydrogen Peroxide, at least 20% strength 1 teaspoonful xanthan gum (health food shops or Ebay) 1/2 teaspoonful 'Vanish Oxy Action Plus' (any 'Oxy' laundry booster will do) 1 teaspoonful glycerine Equipment Gloves and Goggles (Safety First!) 1 UV blacklight lamp Liquidiser or hand blender Procedure Chuck all ingredients except the Oxy into a container and mix until a smooth thick gel is formed. Just before you use it, add the Oxy in by stirring and then brush the mix onto the item to be treated. Stick it under the UV lamp. Check regularly until the yellowing has gone.. ref: http://eab.abime.net/showpost.php?p=467655&postcount=294 Take care! George Rentovich 2009