What to apply before colour & lacquer?

[slim_boy_fat]

For all the paint experts, can you advise on the next stage I need to do?

I've rubbed down some surface bubbling on the bootlid of my BMW, caused I suspect by a previous owner slamming the lid on something not packed in properly and having chipped the paint. Anyway......Dremel, sand paper and then rust converter to stop [yeah, right.... ] it coming back again.




I don't at the moment have any u/coat, primer etc but do have an unopened pack of P38

OK so far....

But, although it's difficult to tell from the photo, there's no real 'step' from the repaired section to the top coat, so mixing up the minimum quantity of the P38 is going to be overkill, not to mention a waste of product for all that's needed. My question is, having read all the posts quoting exopy this and that, Upol and other types, would a few coats of one of these, rubbed down/smoothed or wet sanded prior to painting be OK? Also, any links to small quantities, I don't expect to use much and even 1/2 litre or whatever would be a lifetime's supply.

Excuse my ignorance of such things, I don't generally 'do' paintwork.

 

[the snooper]

If its bubbling you need to take back to bare steel and check if it has gone through the steel if so you need to sort it out as it will bubble through again from the rear you then need to flat a little beyond the repair area and feather out the original paint then prime and top coat, what ever product you choose you will have plenty left

 

[slim_boy_fat]

If its bubbling you need to take back to bare steel and check if it has gone through the steel if so you need to sort it out as it will bubble through again from the rear you then need to flat a little beyond the repair area and feather out the original paint then prime and top coat, what ever product you choose you will have plenty left

It was back to shiny steel with no perforation before I applied the rust converter.

 

[steveo3002]

needs sanding until feathered ...has to feel smooth

rattle can etch might be an option if you want cheap...but wont cover that mess

 

[GW8IZR]

sorry to say that the only way is a good clean down to bare metal, get the filler over a much bigger area and sand to shape.. spot in any holes in the filler and re sand.. then grey prime base and lacquer - don't be frightened of covering a bigger area.

 

[anjum]

As above but use two part epoxy primer on the bare metal before filling and sanding.

 

[slim_boy_fat]

Appreciate the guidance lads I came across some primer [general metal type] I'd forgotten I had while I was looking for something completely unrelated today so have brushed on a first coat - I'll see what it's like [prob on Wed as other commitments mean I probably won't get back to it tomorrow ] then maybe a second coat before sanding etc.

The car's 14 years old with approaching 128k miles up so, although she wears her age well, I'm not aiming for Concours - just something that'll maintain it in keeping with the rest.......

 

[the snooper]

Just bare in mind that unless you flat it really well the brush strokes will show in the top coat

 

[slim_boy_fat]

Just bare in mind that unless you flat it really well the brush strokes will show in the top coat

Thanks It'll be coated..... flatted..... coated...... flatted ad nauseam [if necessary] to within an inch of it's life . As I said, I'm not aiming for concours - at her age most garages wouldn't even entertain as a trade-in, so I'll run her until until I'm in my box, if possible.

 

[steveo3002]

brush on general metal primer may well not like spray paint going on top

if its a cheapie tidy up sand the repair smooth /feather the edges and use rattle can etch - its what a smart repair man would most likley do

 

[GW8IZR]

Thanks It'll be coated..... flatted..... coated...... flatted ad nauseam [if necessary] to within an inch of it's life . As I said, I'm not aiming for concours - at her age most garages wouldn't even entertain as a trade-in, so I'll run her until until I'm in my box, if possible.

even though my e46 builders van is planned to be with me till only the scrap man will be interested I'm just about to put new wings on it. I paid an extortionate 35 quid for the insurance approved panels and the paint we put on them was more expensive!

Anyway.. everything you need for a nice repair on that panel is available from a decent trade paint place - there was a reasonably good one in Inverschneck not far from what used to be McRae and Dick.

Two pack rattle cans work well enough for small repairs and if you buy a can of speed blend you won't be able to see where you have been.

 

[GW8IZR]

brush on general metal primer may well not like spray paint going on top

if its a cheapie tidy up sand the repair smooth /feather the edges and use rattle can etch - its what a smart repair man would most likley do

+1

 

[Maxakarudy]

I think what you find why the bubbling returned is NOT PAINTING the EDGE & UNDERSIDE PROPERLY & only dealing with the face side, its so important to prep the eges to avoid reacurrance like this.

 

[slim_boy_fat]

Thanks again, guys. Because of the size of the repair, I'm going to be brushing the top coat with a good quality artist's brush. I've never in all my days had any success with rattle cans, and it hasn't been for the want of trying..... I have the BMW touch-up paint kit [new] and my [Baldrick-style] plan is to pour a small quantity of the colour & lacquer into a small pot [think....medicine measure etc], mix and brush on from there. Then it can be wet-sanded and compounded, repeating as necessary until I'm satisfied.

I doubt that any traffic I pass will be able to detect it anyway......

 

[Burdekin]

I use this for small chips etc: https://www.cromwell.co.uk/shop/adhesives-and-sealants/structural-adhesives/product/p/MMM7055098R

 

[Dieselman 63]

+1 for bare metal, get the grinding stone head on the dremel and a good light source and grind out all the rust. Then fill, sand, knifing putty etc but remember that the final wet sand should be left for 24hrs as the filler will absorb water. A good tip after priming is to spray over a fine misting of meths and using a light to see if you can find any low/high patches that need working on. Patience is the only thing which will guarantee a good finish. I would stay clear of brush painting a car as nice as this. For a tractor maybe yes!

 

[slim_boy_fat]

@Dieselkid 63 Aye, did the Dremel sanding thing first, even had one of those diamond bits on it too. The 'repair' is only small and I'll be painting with an artist's brush as said.

If I'm not happy I can always start over, I have lots of time but am weather dependent - not having a garage.

 

[Burdekin]

but am weather dependent - not having a garage.

That's what happens when you move away from the Scottish Riviera. ;-)