Brush painting 2k paint.

[Markvh]

Hi,
As mentioned before, I'm fettling up parts of the underbody, mainly seams under the wheel arches, wheel arch lips etc and a couple of very small bits on the upper body. The under arches are stone chip paint, over-painted in colour that is the same as the body (Volvo Flame Red). The paint work was done in ICI 2K paint. The problem I have is the paint suppliers can't get a close enough colour match with 1k cellulose paint but say they stand a much better chance if use 2k paint. I have tried 2 suppliers.
If I can get a really close match with 2k paint, it won’t have a clear coat on top.
a) will it brush paint OK and how much hardener would be required. It doesn't matter if it takes up to a week to cure (in a warm garage) and I'm not fussed about brush marks over the stone chip paint..
b) Is it safe to paint wearing a Gerson B1 face mask as opposed to full on 2k air-fed breathing apparatus. I won't be painting much at a time.
c) How many coats might be required to cover the grey epoxy mastic primer.
d) Would each coat need some prep before applying the next coat.
I want a close a match as possible because I don't want to end up brush painting the whole of the underside of the wheel arches! Also I don't want to be spraying because I think the masking would be too fiddley plus I would need specialised breathing apparatus and it's not worth sending to a spray specialist.
Thanks very much.
Mark

[flying farmer]

Can't see any reason it would not brush on. I have used 2K to touch in stone chips in the past.

I would just use the recommended percentage of hardener, you won't need to use thinners for brush painting.

I used a filtered face mask for spraying 3 cars with 2K and I will be doing my Estate this Summer. Provided it is a good fit and you don't have a beard there won't be a problem. When the filters on my first mask became tired I could start to smell paint when spraying.
If it is working properly you will not be able to spray anything!
I don't think you will need any between coat prep unless you need to sand out brush marks, I don't do any rubbing down between spay coats unless I get a run in the paint.

Neil

[Goldstar]

I agree with Neil. I’ve been spraying 2 pack filler primer with a charcoal mask and loads of ventilation. I know people will tell me I’m riking life and limb but it’s one car not my full time job and I’ve done my own research and risk assessment

If you’ve got any larger, flattish areas you could also try a small foam roller which might dry better than a brush? You may not get brush marks but I’d be surprised if you didn’t so if that’s the case you will need to flat with 3000 and polish.

Get a sheet of scrap steel and practice on that?

[trunt]

+1
Someone is going to disagree but my feeling is that spraying 2 pack once every 8 years or so is a lot different to doing it every day. Good point on the beard, I shave clean when spraying and cover up well including the eyes. I use good quality disposable 3M masks (7192 series) and buy a few so I can regularly change them, certainly a fresh one every session - well before I smell anything!. As soon as I'm done a coat I get out of there into the fresh air!

My local paint suppliers can make rattle cans of paint for you. I had one made to colour match my paint. I'm not sure on how that works as far as 2 pack goes but it could be a solution?

Terry

[Gemini 51]

There's no problem brushing 2K paint, if you use a good quality brush the brush marks won't be an issue, I would put approx 10% hardener in, that will give a good viscosity for application and it will be hard enough the next day for a light "Scotchbrite" pad and another coat. Two coats should be enough but reds can be a pain to cover, so repeating the process won't be a problem, and only mix up as much as you need, you can't put the leftovers back in the tin like nitro.
Be aware that the hardener comes in different drying speeds, for brushing a fast one will be better. 3M do a good face mask, I just forget the part number, for around £20, we call them fly masks but make sure you have good ventilation where you paint it, and use latex gloves or similar.
Like most things used and handled correctly there won't be any health issues.
Good luck, you'll surprise yourself with the results

[Markvh]

Thanks very much guys. That's decided me, I'm going for the 2 pack. A couple of more questions.
I need to paint the flange lips of the wheel arches, Only about 7 mm or so width. Should I paint one coat on, let it fully cure then feather it back before putting the next coat on or put 2 overlapping coats, leave to cure and then feather edge? I don't want to be feather edging onto the wing panel; itself. I think there is enough width on the flange to do that.
Is it possible to brush paint a second coat after a curing time so the brush doesn't drag but before the first coat needs a rub down or scotching? Or is it best to wait until it is fully cured before putting a second coat on? ie is there an ideal time window?
Today, the paint suppliers have given me a data sheet for the 2K, that suggests 2 parts paint to one part hardener which equates to 50% hardener. This should give a pot life of about 2 hours.

Gemini 51, you suggest approx 10% hardener. Does this make it brush better but give a longer pot life and longer to cure. The data sheet gives several hardeners, I'm thinking of using the 8000 extra rapid which is for temperatures below 25 degrees C (or the 9000 Super rapid for touch ups below 25 degrees C). Or should I put in the recommended ratio of hardener as Flying Farmer suggests? Bear in mind apart from the wing wheel arch lips and a bit under the bonnet and engine bay the remainder is over stone chip paint and seam sealer.
Thanks very much again, your advice has been really helpful to me. I'll let you know how i get on!
Mark

[Gemini 51]

The "recommended" level of 2 parts paint to 1 part hardener is for spraying, that will give the correct viscosity for gun use but will be too thin for brushing, as with all painting operations don't overload. With spraying 2K you would apply a medium coat flash off for 5 mins then full coat, the same principle applies with brushing, brush on a coat, leaving it 5 mins then apply another coat, leave it 'till the next day then if coverage is not satisfactory scotchbrite and re coat.
All the recommended times etc are usually based on a 20°C air temperature so time adjustments may be necessary.
Also by using too fast a hardener it will cause shrinkage and reduce the gloss, but will cut back and polish if needed.
By being careful with your brush you may be able to "feather" the paint edge, practise on something first, good luck.

[Gemini 51]

Hello again, the mask that I suggested earlier is a 3M part no 4251 organic mask and comes in a sealable bag and are available on line for £17.99, I've used them for years.

[Markvh]

Thanks. Another question.
Where the new brush painted edge overlays the existing paint. What grade wet and dry should be used to rub the edges down flat with the existing before rubbing down with 1500 to 3000 grade paper and then cutting and polishing back? I don't want to use too coarser paper that takes even more sanding back to lose the scratch marks.
I have sanded the primer and existing paint with 600 grade wet and dry ready for painting over with the 2K paint. It will probably be at least a week between painting and then rubbing the edges down etc.
Thanks very much for your help.
Mark.

[Ian928]

I have brushed 2K epoxy primer on my Stag Top rotet bare metal after localized sand blasting. The only problem is that there are more brush marks than I would like. Ian going to spray the whole are with filler before the Final coat so I think I am Ok.

[Motorsport Micky]

"Ian going to spray the whole are with filler before the Final coat so I think I am Ok.

"

P38 ? or primer filler ? be specific.

Micky

[Goldstar]

"Ian going to spray the whole are with filler before the Final coat so I think I am Ok.

"

P38 ? or primer filler ? be specific.

Micky

I’d be interested to see how you spray P38, I think we can assume he means filler primer

[CJG]

I’d be interested to see how you spray P38, I think we can assume he means filler primer

Here you go, one P38 spray gun.

https://www.yellowoctopus.com.au/products/kidz-labs-catapult-making-kit

[Goldstar]

Very good

[Ian928]

"Ian going to spray the whole are with filler before the Final coat so I think I am Ok.

"

P38 ? or primer filler ? be specific.

Micky

Sorry! Filler Primer from rattle cans. In norwegian Filler Primer is shortened to "Filler", probably because Filler has a Norwegian name so no one confuses them...