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Help with clearcoating


keveuh
01-11-2013, 08:32 AM
Hi everyone, I need a little help with clearcoating.

I'm working on a Tamiya 2CV. First off this what I use:

- Alclad grey primer
- Zero TS-44 brillant blue
- Tamiya TS-13 clear completely decanted, this means that there's no propellant left since I decanted everything in a glass jar.

The first time I had clearcoated it felt like my first coats were too thin and I had a weird white powder-like thing on my model, I could more or less remove that by appalying thicker coats. But at the end the surface was too rough and I had to sand a lot and I went through the clear so I decide to strip the paint and restart from zero.

In the meantime I read a lot on the web and often a little product was mentioned: leveling thinner ! So I bought a bottle a Gunze leveling thinner and I decided to use it with the Ts-13 and spray at the lowest pressure possible.

I then sprayed 4 cups (I think) of clear.
1 = 3ml of TS-13 + 2ml of thinner, PSI 15
2 = same as above
3 = 3ml of TS-13 + 3ml of thinner, PSI 10
4 = same as above

I put 2 mist coats + 2 wet, at least I tried to do so. At the end I could really see some nice shiny and smooth surface... until now.

Few days later, today, I took pics to show you:

http://image.noelshack.com/minis/2013/02/1357910234-prob-peint-1.png (http://www.noelshack.com/2013-02-1357910234-prob-peint-1.jpg)
http://image.noelshack.com/minis/2013/02/1357910235-prob-peint-2.png (http://www.noelshack.com/2013-02-1357910235-prob-peint-2.jpg)
http://image.noelshack.com/minis/2013/02/1357910235-prob-peint-3.png (http://www.noelshack.com/2013-02-1357910235-prob-peint-3.jpg)
http://image.noelshack.com/minis/2013/02/1357910236-prob-peinture.png (http://www.noelshack.com/2013-02-1357910236-prob-peinture.jpg)

On the last pic you can see a weird thing, my guess is too much paint that ran off. But you can see that the surface is a bit rough and mostly not so shiny it looks like semi gloss, and I don't know why. That's where I need your help ? I'm planning to sand and polish which could very well do the trick or should I apply more clear ?

I have a bottle of Zero 1k that I keep for other models I could use that too of course but I don't want to waste my TS-13 therefore I want to use it.


Thank you !

iceracer1
01-11-2013, 10:55 AM
What kind of needle+nozzle do you use and what pressure? You need to thin the paint just like milk thickness.

I spray with a 0.4mm needle+nozzle with a pressure between 2 and 2.5 bar.

Kris.

keveuh
01-11-2013, 11:47 AM
I use an Iwata HP CR with a 0,5mm needle. the pressure I wrote in my first post: 15/10 PSI.

stevenoble
01-11-2013, 12:01 PM
The basecoat has sucked all the gloss out of the clear coat. Looks great at first but overnight drying and the fantastic gloss you had is gone. That's because the clear has sunk into the basecoat. Basically the basecoat has acted like a giant sponge and absorbed the clear. Solution..?? Use wet and dry paper, gentle grade 1500 or 2000 if available (used wet) and sand the surface smooth, but be very careful not to rub through the basecoat and back to the plastic. Go slow and easy and check your progress often..!!! Once you have taken out the bulk of the texture, dry off the parts and shoot a fresh coat of clear. You may have to repeat this again but each time the gloss retention will improve and you will have less absorption into the basecoat. Once you have it to a level you're happy with allow to dry thoroughly and then polish to a perfect finish. Pressure is a touch low I feel. I use 20-30 psi when clearing. When using clear you actually want a good throughput from the gun. A dry under pressured coat of clear will not achieve a nice wet gloss.
Only way around this problem is to use 2K clear. As this is a high build clear you get very little shrinkage or absorption into the basecoat and what you have experienced here is practically non existent..

keveuh
01-11-2013, 12:14 PM
Thanks Steve, I read different people saying they had an easier time spraying at very low pressure and very thinned clear to spray wet coats so I thought I'd try and yes it was fairly easy. I didn't know the basecoat could absorb the varnish !! The 2K seems to be the magic stuff to get a perfect result every time but the toxicity of it is a real concern to me. I don't know neither my wife nor my kid to breath that thing, I do have an effective spraybooth but I don't have any sufficient respirator mask, I guess I'll think about it.

So solution is: sand carefully to get rid of the orange peel, and shot some more coats, wet coats I guess wait and repeat the procedure until the shine is good enough for me. So nothing is wrong so far in my job then.

Thanks !!

stevenoble
01-11-2013, 12:22 PM
Thanks Steve, I read different people saying they had an easier time spraying at very low pressure and very thinned clear to spray wet coats so I thought I'd try and yes it was fairly easy. I didn't know the basecoat could absorb the varnish !! The 2K seems to be the magic stuff to get a perfect result every time but the toxicity of it is a real concern to me. I don't know neither my wife nor my kid to breath that thing, I do have an effective spraybooth but I don't have any sufficient respirator mask, I guess I'll think about it.

So solution is: sand carefully to get rid of the orange peel, and shot some more coats, wet coats I guess wait and repeat the procedure until the shine is good enough for me. So nothing is wrong so far in my job then.

Thanks !!

Yes the health issues are a concern with 2K. I've even been researching them myself and it makes for interesting reading. A full air fed mask is recommended, and they are very expensive, plus you need a separate air supply to power it and provide clean, moist air to the mask, so it's quite an outlay to get properly set up..
You've done nothing wrong so far. I have the same problems as you've had here when I use a 'normal' clear. But the flatting back, re-clear process usually gets it up to a nice finish and then polishing it gives it the final touch. Patience and a little time will see you right :)

iceracer1
01-11-2013, 01:17 PM
If you are afraid of the toxicity of the 2k paint why are using the zero paints colors? They are very toxic as well.

A good spray mask doesn't cost a lot. I use a 3M mask with carbon filter and dust filter and it's for the automotive industry. Ebay is full of them and they cost around 20-30 euro's.

I always like to spray with a good pressure when I clearcoat my models. Else the clear will dry before it hits the model, and that's the problem you had the first time when the white stuff came. I also use a low distance between model and airbrush (10- cm)

Kris.

keveuh
01-11-2013, 02:06 PM
I think the 2k is urethane and therefore is more toxic than the basecoats, I could be wrong but I think so. I already use masks but it's more like dust masks. I judge they are enough so far for the fact that I don't smell anything when I spray. But I'm checking to see where I could get a good full mask for both vapor + dust without paying too much for shipping and where I can easily get new filters for it.

About the pressure, most of the time I see people recommending as low pressure as possible, and others say they use a pretty high pressure. So it might be a matter of what product you use + what airbrush/airgun + distance to the model + whatever other factors apply.

GirchyGirchy
01-11-2013, 03:05 PM
I think the 2k is urethane and therefore is more toxic than the basecoats, I could be wrong but I think so. I already use masks but it's more like dust masks.

Minimum for that stuff is a respirator, like this:

http://www.melbran.com/Pictures/Respirator/52P71.jpg

If you're using a mask like this:

http://www.lifeprotectors.com/firstresponder/8210.jpg

Then it's not enough. Get a respirator that's made for paint, they're not that expensive.

You should probably also have a paint booth that sucks the paint mist out through a filter. Careful with a fan as well.

keveuh
01-12-2013, 02:37 AM
I have a spraybooth with a dual filter, a fan that blows directly outdoors. As I said I'm looking for a place where I can get one of those good respirator mask, I'm in Finland and it's not easy sometimes to find equipement.

keveuh
01-12-2013, 08:11 AM
A little update on my work on the car. While I was sanding I removed some basecoat paint at 2 places. One of those places is not a big deal because it will be covered later whith another color, now the other place is a small dot that may look like a refection spot. So here I have 2 solutions:

- I spray a dot of basecoat and hope that it won't react to the clear lacquer
- strip the paint off the body (for the 3rd time) and buy a can of TS-44 and spray with the can, because these kind of cars, vintage cars have difficult shapes to reach while painting and sanding and it's a pain to work on them !!!

ZoomZoomMX-5
01-12-2013, 09:01 AM
If you are airbrushing and even contemplating stripping the finish, I'd definitely consider a careful spot-in of the base color in the affected areas, then re-clear...carefully. Don't drown it (either base or clear), take it slowly (mist the spot-repairs, and mist coats leading to wet coats for clear), and it will probably be okay. I find it much easier to fix minor issues rather than going nuclear and stripping/starting over, with no guarantee it won't happen a second time. Too many people give up too easily.

Even w/the spot repairs, your subsequent finishes should be better and better; each step of wet sanding/recoating should result in smoother and smoother final finishes. If you get a problem in the clear, stop, assess the situation, you might want to let it cure, sand out the imperfections, and continue applying clear. With a 2CV, it doesn't need to be ultra-glossy, but it should be smooth.

keveuh
01-12-2013, 09:12 AM
Thanks for the help, I'll follow your tips. And I didn't dare to sand too much because since the clear was absorbed it's like the layer is quite thin and I don't think should try to sand it so smooth, I don't want to risk removing more basecoat. So I'll spray a tiny bit of blue just where I need and then redo a whole clearing session.

keveuh
01-14-2013, 03:12 AM
Minimum for that stuff is a respirator, like this:

http://www.melbran.com/Pictures/Respirator/52P71.jpg

If you're using a mask like this:

http://www.lifeprotectors.com/firstresponder/8210.jpg

Then it's not enough. Get a respirator that's made for paint, they're not that expensive.

You should probably also have a paint booth that sucks the paint mist out through a filter. Careful with a fan as well.


I'm looking for a respirator but I need help for that.

There are different kind of filters for the masks, some for Organic/inorganic vapors, gaz, amonia etc.... And I wonder what kind of filters do you need to be protected against:

1 - enamel paints + white spirit
2 - lacquers + their thinners and cleaners (Acetone, Tuloene)
3 - automotive paints + thinner/cleaner (like the Zero basecoats paint/thinner)
4 - urethane 2k varnish

I have 2 mask in mind, either a 3M 7500, or a Scott Profle 2 but I just need to know that filters to buy.

Thanks !

iceracer1
01-14-2013, 06:44 AM
You need a p1 filter for the dust and an active carbon filter for organic vapors.

The 3M 7500 mask already comes with the right filters.

Kris.

keveuh
01-14-2013, 07:46 AM
You need a p1 filter for the dust and an active carbon filter for organic vapors.

The 3M 7500 mask already comes with the right filters.

Kris.

Well actually everywhere I checked the 3M 7500 doesn't come with any filters. But you say P1 + A1 then. On Hiroboy they have a respirator with filters only rated A1 and I cannot believe they would sell inappropriate filters when they sell automotive/urethane paints. But I'll check for P1 + A1 filters because it's better to have too much protection than not enough.

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