chemical removal of yellowing white gel ?

[rwatson]

Originally Posted by Wynand N

here is the link for the applet we use. Just drag the colour squares over each other and see what happens. Adjust shades of blue, red and green on the scales to suit - or go about as describe above somewhere. Enjoy
http://www.lon-capa.org/~mmp/applist/RGBColor/c.htm

Oooh er - how does that help mixing stuff? It doesnt even show the percentage figures (in precises numbers) of each primary colour.

If you monitor isnt correctly adjusted, the colours themselves are off.

There must be a better way - something commercial like they use at Paint Shops.

[ondarvr]

We use a computer with a color eye similar to a paint store, it needs to be calibrated for the exact pigments being used, plus be recalibrated for each new batch of pigment. There are people that can do it very well by eye, but its almost a lost art.

[Wynand N]

Originally Posted by Wynand N

It pays however to know what to add and how colours are changed.

Watson, I never said it is perfect, but take a lot of sweat and guesswork out of it. I will repeat again - first of all get the three main colors adjusted on the slider until it matches your color needed - sometimes you would only need to mix two colors for a match.
However, if you have a match, check and see how your three main pigments compare to the ones on screen and adjust the color intensity of your pigment colors to match. Mix them up and you will have a close to perfect match. If a bit off, adjust the color and read the sentence in the quote above.

Unfortunately, I write this post from my house computer and the applets are not on my bookmarks here, but there is another link we use together with this basic applet mixer that actually shows how colors changes with different colours added and this let you know what to add to get a color darker/lighter or to fade it a bit....
As said, we do repairs of gelcoats quite successfully regularly using this method with the limited amount of color pigments we have.

Remember, necessity is the mother of all invention....