geekhack
geekhack Projects => Making Stuff Together! => Topic started by: fohat.digs on Tue, 25 February 2014, 17:34:50
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I have started threads like this in the past, and have not gotten much help.
My success rate is low, although I do get an occasional complete success so I know that I must be on the right track.
There must be some trick or adjustment that I am not quite getting right. I am going by the recipe on the web site:
http://retr0bright.wikispaces.com/Retr0Bright+Gel
After trying to skate around using the exactly proper ingredients, which are not easy to find off the shelf, I have tried to formulate it just right. I have bought hydrogen peroxide at about 3% and boiled/simmered it down to a third or a quarter of its original volume to get something in the 10%-15% range that is recommended. I have plain liquid glycerine in a little bottle and dry xanthan gum powder. I have ordinary "Oxi-Clean" laundry powder (white with some blue spots). (Earlier, I had trouble finding glycerine so I tried the arrowroot formula which just made a white crust.)
So I mixed up about half a liter of the primary components (less the Oxi-Clean) to a nice thick gel consistency in a food processor and stored it in a dark container.
For the final mix, I dissolve a fraction of a spoonful of Oxi-Clean in a couple of spoonfuls of hot water, add it to a large dollop of my original gel, and buzz the whole thing in the food processor until it is a nice even gelled froth. (If it sits for a few minutes it will bubble up and double or triple in volume.)
I paint this on my surface (usually an old yellowed case) in a medium-thin even coat and set it on the front porch rail in the sun.
It takes something less than an hour to dry out to a crusty glaze.
My thoughts on the recipe are that:
(1) the amount of "oxi" is very low and should be increased
(2) more glycerine would keep the mixture in a gel state longer, since it may stop working when it dries out
I would love to hear other thoughts or opinions on this.
Thanks! Harry
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I just do straight liquid hydrogen peroxide developer, around 25-35%. After a bunch of research, I basically came to the conclusion that the OxiClean is unnecessary and can often be the cause of headaches. One of the common problems some people have with retrobrighting is "blooming" and it seems to be more common in those recipes that use OxiClean and gel state peroxide.
Liquid peroxide can be a PITA since some of the caps will float, but a sheet of acrylic on top of them or something similar will keep them submerged without really affecting the time too much.
From my understanding, you also don't want to let it dry, you should be wrapping it in plastic wrap if you're doing a gel state.
Lastly, keep in mind that retrobrighting does permanently damage the plastic (http://aktuelbevaring.natmus.dk/afrensning-af-plast-med-retrobright.html), so don't do it on things that are already brittle or where you're concerned about the long term health of the plastic.