80 grit too much?

[caduceus]

Hi all. Is 80 grit sandpaper too rough to prepare a fibreglass body (TVR Chimaera) for a colour change?

There is other stuff to do to the car as well like GRP repair, etc, but I want to make a start on sanding the whole body, so the unblemished bits are ready for primer.

Many thanks
Cad

[Hainey]

In a word, yes. Lowest I would go/have gone on fibreglass is 120.

[caduceus]

Thanks for the quick reply.

I've got some 180 grit so I think I'll use that.

[Hainey]

caduceus said:

Thanks for the quick reply.

I've got some 180 grit so I think I'll use that.

180 is perfect. Pretty forgiving as well if you have a tendency towards the enthusiastic!

[paintman]

Decide which primer you intend to use.
Read its Technical Data Sheets which give you all the details you need for prepping the surfaces, applying the primer and then prepping the primer for subsequent colour and clearcoats or topcoats.
Follow those instructions.
Anything else is just guesswork.

A random example:
http://images.vinnybyrne.com/media/mconnect_upload...
Note that for GRP it specifies 240 grit used dry & for a painted surface 320 used wet or 240 used dry.


If you use too coarse a grit you'll have hours of fun flatting the primer & you may find that subsequent shrinkage gives you a lovely sandscratch finish. Which will be only too obvious.
http://www.glasurit.com/uk/sanding-marks

Edited by paintman on Saturday 3rd June 21:53

[caduceus]

Thanks for the replies so far chaps.
Made a start on it today with some 240 grit and a Meguires backing pad. Rhino strips in 240 grit would have been better but needs must.

Any more info is greatly appreciated.