Paint chip down to metal - need to undercoat?

[smack]

Hi guys,

I have started to fix up chips on the paintwork of a BMW using guides I have found on net such as detailing world using touchup paint, and will be wet sanding it back when I get up to that stage. But I have one largish chip (maybe 4mm chip from memory) on the edge of boot, from when the previous owner caught it on something.
It has chiped back to metal, and has very slight surface rust - probably happened quite a while ago.
Do I need to use anything during clean up (apart from cleaning the metal with wet and dry), or use anything as a base coat under the touch up paint?

Thanks,

Stuart

[eldudereno]

It's never easy to get rid of rust once it's started but I would put some rust killer on it first then build up the paint in thin layers allowing each layer to dry thoroughly before applying the next.

[PJ S]

Contact a local repair place, and ask them if the primer is separate to the anti-rust treatment.
If so, and not easy to use on the type of repair you're facing, contact Bilt Hamber and see if their rust removal/anti-rust treatment products would be suitable.
I'm thinking Hydrate 80 and/or Deox Gel would be suitable.

Edited by PJ S on Thursday 7th August 01:43

[smack]

PJ S said:

Contact a local repair place, and ask them if the primer is separate to the anti-rust treatment.
If so, and not easy to use on the type of repair you're facing, contact Bilt Hamber and see if their rust removal/anti-rust treatment products would be suitable.
I'm thinking Hydrate 80 and/or Deox Gel would be suitable.

Hi PJ,

I have been reading up on Bilt Hamber's products, and that would be exactly what I was after. A quick google and I was sent over to DW, and few other car forums with good reports of their products.

I would guess the chip happened a few years back, but the car had not been driven and stored in a garage. It is only a small area, and light surface rust, but I want to deal with it right.
So reading up on all this, Deoc Gel on the metal to eat away the rust, and Hydrate 80 on top to seal and chemically seal the metal? Then I can use touch up paint on top?

Thanks again

[PJ S]

I just spoke this morning with them about this for clarification - just Deox Gel 2-3mm thick, cover with cling film overnight.
Wash off, and then prime, and touch up.
Got a few myself to do on mine - so that's what I'll be doing.