I would really like to find some blue primer which is the same as my gelcoat (or even close). Looking around my suppliers I can only find the usual red, grey, white or beige.
Is it possible to mix a little pigment into a white primer to get the required shade?

I used to tint primers back in the cellulose days, just add about 5% of the top coat to the primer.

The problem these days is getting a compatible pigment to add. Clearly cellulose top was compatible with cellulose primer!

Erm, Why on earth would you want to tint a primer?
By it's own title "primer" it is a primer and should be treated as such. It is a primer or undercoat for the top/finish coat. It should be covered by top coat so you can't see it anymore.

Surely if it is the same colour as the gell or top coat then you won't know if you have covered it properly.

Primer as a paint is porous and can absorb moisture if not sealed with a top coat. That is why you often see part repaired cars that are left in primer with rust coming through the paint. It does not seal the metal away from moisture.

On fibreglass it won't go rusty, but it will flake off after a while!

Terry

Many colours are translucent, and it is the number of coats that builds the final colour, especially yellows and pale blues.

So any advantage you can get with the primer is a bonus. It means a lot less fading out.

Mark makes a good point but it is not really why I want to match the colour.
I am doing extensive mods to my fibreglass bodywork and the result is a mish mash of all sorts of colours resulting from various fillers & primers. So.....

1. I am not an expert body modder and I am more likely to see imperfections if it's all the same colour.
2. I would like to get the car SVA'd before I paint the car (just in case of any last minute mods) and I just wanted to get the car to look a bit more respectable - pure vanity I suppose