Ok yeh I meant anodising then, tried caustic soda but didnt work, possibly because I used a weak soultion. I cut it down to 2bolt because I never actually used to use the top 2 bolts in the booster, just the bottoms other wise it was too stiff, but the main reason I did it all is because it different! And yes caustic soda would have worked on the booster but it would of taken all the blue off, I wanted half blue half silver, becuase there is a little ridge between the blue and silver it meant that the sandpaper didnt touch the bottom, thus leaving a neat line between the two colours.