To Retrobright or not to..

[danbeaver]

The Retr0Brite process uses 12% Hydrogen Peroxide to whiten the plastics, but it leaves microscopic "pits" in the plastic that allows it to re-yellow; a clear, matte coating of a polyurethane spray paint will seal it nicely and is undetectable visually leaving a new appearing plastic part (if the Retr0Briting was done correctly).  Metal cases were originally painted with enamel and after cleaning and sanding should be repainted with enamel, although it takes several days to dry; the best approach is to take it to a car paint place and have them match the original color and paint it there.

[danbeaver]

EAB has a "Sticky" Guide in there Hardware Support section, but a beauty supply shops (Sally's in the states) will sell 16 Oz of 40-Volume Creme hair developer (12% Peroxide) for about $12 USD that easily coats plastic parts; wrap it in plastic (Saran Wrap) after applying a thick coat and leave it in the sun. On a warm, sunny day in the Midwest US, the majority of the yellow is gone in 4 hours.  Once whitened to your liking, rinse off the coating and let dry overnight, then spray the clear, matte coat to protect it.  

Uneven coating will result in streaks and require further treatment; not washing dirt off the plastic before treatment will do the same; not taping the plastic wrap on will let the wind blow it loose and areas will dry out and this stops the whitening process; not wearing gloves will sclerose your skin (which looks and feels funny).  "Nothing is 'fool proof' because fools are so ingenious."

[danbeaver]

So I decided to retrobright the A4000 I have. I was wondering if I need to protect the Commodore logo. Anyone?

Yes, a simple cover of Scotch clear tape (cut to not cover any of the plastic you are whitening) will work fine and peel off easily afterwards; I use an X-acto knife to trim up mine.

[danbeaver]

I have painted two plastic fascia that did not look "good enough" once retr0brited, but I prefer the original look and the clear coat takes no time to add and dry.  I spend my most time wrapping the retr0brited parts in Saran Wrap and taping up the backs than anything else; on a warm day in direct sunshine 90% of the "work" is done in 4 hours, and is completed in 6 hours.

[danbeaver]

I use adhesive masking tape cut with a hobby knife to protect the logos; all you need to do is make sure the peroxide doesn't get to the colors.