Bumper Paint Problem HELP

[azazelus]

Hi Guys

I have a black sapphire BMW z4. I wanted to paint a small square from the front bumper due to some deep scratched.

I am painting this with rattle cans ( i know it cant be a professional finish but if you know what you are doing you can get it close)

I did all the process .. Primer , rub it down, put the colour base coat ... Clear on top of all.

I bought a mixed colour match paint from Halfords.

The problem is that after i sprayed the new paint looks granulated , feels like sandpaper. ( Now i dont know what is the cause of this .. the nozzle from halfords spray or bad mix? I did a lot of wheel refurbs with rattle cans and all look very smooth and high gloss.)

I think that is why the gloss look from the clear coat doesnt look the same with the original clear on the car. it looks dull . I applied already 5 coats of clear so this is not the problem.

I want to rub down again with 1500 sandpaper till the black colour is a really smooth surface then apply clear again.

My main concern is that i rup the sapphire black .. it will look different after clear is sprayed?

How can i fix this?

 

[Wildfire]

Ok, so here's how to do a semi-decent blend. You'll never get a perfect match with cans, but it can be ok.

When you mask off the area you need to over-mask and the curl one edge of the tape up. This way when you spray, you do not get a hard line when you spray. Cover the area in black. When spraying, you need to flick the spray pattern away from the surface as well, this helps with blending the colour. When you're happy with the black remover the tape and then over-mask a much bigger area with the same technique. Then repeat the same with the lacquer.

When flatting down, you again need to over flat the area and try to feather the colour edges. Do this gently especially when you are at the edges.

The most important thing is to let the paint and lacquer harden before you rub down and the polish up. If you have access to an infrared lamp/heater, a bit of time under this would be ideal. Sadly rattle cans never really go hard.

My advice is to let the clear coat harden fully, with a lamp assistance if possible, then gently flat the clear coat, to remove the orange peel effect. Do this with a bucket of water with some washing up liquid in it for lubrication and some 1200/1500 wet and dry paper, and a soft block. The black is important to try and level off the paint/clear coat. Use a micro fibre cloth or similar to dry down the area. You will then see the low/un-flatted areas. Careful not to go through this. Once you have an even surface, get some 3M Hand Glaze/Faraclea G3/Cutting Compound and polish up by hand.

If the finish is REALLY rough, you may have a reticulation on the panel. This could be due to the presence of silicones or other contaminants on the surface, or possibly too much moisture when spraying. In this case, you will need to rub down (use 600/800) and re-paint.

When body shops do a bumper they often paint the damage, but re-lacquer the whole panel.

Either that or cut you losses and get chips away or similar in.

 

[azazelus]

Thank you for answer Wildfire.

I do not have a problem with the edges. I did the feathering really nice for both paint and lacquer.

The only problem i have is that the paint under the lacquer is granulated. When i put my hand it feels like sandpaper. I think that is why it looks so dull and more grey than black from an angle.

There were no chemicals on the painted surface. I cleaned it twice with special cleaning spray before painting. I painted in a garage 2 days ago. Bit of a cold but dont think it is too much moisture.

The garage is like an underground parking and it is really big. The temperature was like 9 degrees C.

The granulation is not too big. I think if i go with 1500 sandpaper it will rub it off.

My main problem is that i am trying to understand how much do i have to rub ? Just to rub the lacquer to make a smooth surface or go deeper till i reach the paint and make it smoother?

I am not really sure about the thickness of the lacquer that is why i thought maybe it is better to rub it down ( to make it a smooth surface) then spray lacquer again?? And then maybe after 3 weeks i can rub it down and polish it. It should look shiny from lacquer in the first phase. Now it looks dull and granulated.

Lets say the lacquer will go off and i rub some paint with 1500 grit. Will that affect the final colour for sapphire black?

Is this paint a metallic one? I didnt see any perls inside of it.

 

[cj10jeeper]

Sounds like you simply sprayed too little, such that you did not get a wet finish and the paint landed semi dry and just built up ever rougher, therefore felt like sandpaper. You need to get the spray wet enough to flatten without too much to run, which is always an issue with rattle cans, especially on a vertical surface. You can't flat the base paint on metallic as you run the risk of changing the colour or finish and it'll never match.

Given that you've added 5 coats of lacquer I would now flatten it off with 1,500 then progress to 2,500 and if you can get it 3,000+ as Wildfire suggests with block, water and lubricant. Take care and time or you'll just punch through the lacquer. Machine polish it and see what you've got. Nothing to lose at this point.

If you don't like the result back to flat and start again.

Personally I'd never go near my Zed with a can and always spray using a gun, proper paints and lacquer, painting whole panels at a time.

 

[azazelus]

Thanks for your answer.

But if i rub down the area with 1500 grit and spray lacquer again it will have the gloss finish?

 

[cj10jeeper]

Sure if you can flat it off and not break through the lacquer then you'll be fine. You can add more lacquer in a thin wet layer and once hardened smooth with 2500+ and polish the area to a shine. Wax in a couple of months.

 

[azazelus]

Ahh .. perfect.

i will try this tonight.

Thanks a lot.

 

[Wildfire]

Your best bet is to let the lacquer harden for a few days, keep it clean. Then do as I described:

Flat the clear coat, to remove the orange peel effect. Do this with a bucket of water with some washing up liquid in it for lubrication and some 1200/1500 wet and dry paper, and a soft block.

The block is important to try and level off the paint/clear coat. Use a micro fibre cloth or similar to dry down the area. You will then see the low/un-flatted areas. Careful not to go through this. Once you have an even surface, get some 3M Hand Glaze/Faraclea G3/Cutting Compound and polish up by hand or machine polish after.

The polishing with the cutting compound is whht will make it shiny with a gloss finish.

 

[cj10jeeper]

Ahh .. perfect.

i will try this tonight.

Thanks a lot.

Bit too cold and damp to spray tonight unless you have a well heated (and ventilated) area.

I've just been flatting and machine finishing a bumper this afternoon and my hands were freezing, in a garage...

 

[azazelus]

Hi Guys

It worked. With 2500 Grit and then with polish i got exactly the same shine as original.

Lets hope it will last

 

[cj10jeeper]

Hi Guys

It worked. With 2500 Grit and then with polish i got exactly the same shine as original.

Lets hope it will last

Good - a result

Glad you go thee without the need for any further spraying.

Leave it a week or so until fully hardened then you can give it a final polish and wax.

 

[azazelus]

Thanks a lot.

I hope it will last for a while. I noticed yesterday that the paint is really thin


I wonder .. Can apply this technique for refurbishing wheels? When i did some wheels in the past i just applied the lacquer and i got a nice shine.

 

[cj10jeeper]

Thanks a lot.

I hope it will last for a while. I noticed yesterday that the paint is really thin


I wonder .. Can apply this technique for refurbishing wheels? When i did some wheels in the past i just applied the lacquer and i got a nice shine.

If you look at a rattle can and consider of the total volume that it contains, of which there is a big air space and lots of propellant, then you can see why the resulting paint is thin - there's hardly any in it...

By technique I assume you mean spray, lacquer, wet sand and polish? Then yes, but try to spray wet and need less sanding. You'll also be at much greater risk of going through the lacquer with lots of corners and angles, but equally the finish is a lot more forgiving on a wheel than a visible panel.

 

[azazelus]

Thanks

Well if it last one year im ok with it. By then i will get a proper gun... Actually is not about the gun .. is about the compressor. i dont have a garage.. i have only some underground parking and i cant put the compressor in there.

I was wondering if an airbrush kit ( as a small piece of equipment) will do the job better that rattle? I mean even if its a pain will it do?

 

[cj10jeeper]

Thanks

Well if it last one year im ok with it. By then i will get a proper gun... Actually is not about the gun .. is about the compressor. i dont have a garage.. i have only some underground parking and i cant put the compressor in there.

I was wondering if an airbrush kit ( as a small piece of equipment) will do the job better that rattle? I mean even if its a pain will it do?

Understand. I'm fortunate to have a large garage and have built in a decent compressor and airline set up. Never used an airbrush but it's for even smaller areas so doubt it will be any good.
Are you aware that proper paint shops will make up aerosols to your paint code which are much bigger, better match and work better than the tiny Halfords sort? That's what I'd get. For your wheels then you can have any colour you see on any car.

 

[azazelus]

I am having a hard time finding a paint shop near Woking area .. I am still searching online

 

[cj10jeeper]

I am having a hard time finding a paint shop near Woking area .. I am still searching online

I'm sure there are some around. Cars crash in the Woking area too

Look under 'automotive paint suppliers'. I can see several in the area around Woking, but don't know it well.

 

[Wildfire]

Often body shops will do it if you ask. There is a good place near Croydon who may send it out. I'll see if I can dig out the details.

As above. Wait a week or so then polish again and wax for protection.

My family are all into cars or bikes so luckily we have a large compressor and a bunch of spray guns. Once you match the colour it is really down to the gun and your skill.

Glad you managed to get it sorted out for minimum costs!