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Author Topic: Finish coat problem  (Read 11520 times)

nicoga3000

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Finish coat problem
« on: January 08, 2013, 01:06:42 PM »

Hi all!

I recently started getting into taking kits beyond OOB status.  I wanted to practice with a cheap kit first, so I found a Kotobukiya Mega Man to work on.  After about a week of work, I got him finished up!

Before:


After:


BUT!  There are issues.

I should explain what I've done so that (maybe) the issue can be made clear.  All painting was done via airbrush, thinned to skim milk consistency.

First, the kit was snap fit.  After which, the kit was taken apart and placed in two piles (light and dark blue).  I did a mild sanding of the kit before priming.  I didn't use a primer, though...I used Tamiya XF-19 (the temperature is too cold to go outside and do a spray can here in the midwest USA).  Here's the paint schedule:

Prime: XF-19 Sky Grey
Armor: 70% X-4 Blue, 30% X-16 Purple
Skin armor: 70% X-2 White, 30% X-4 Blue

After these all dried, I did a thin coat of Krylon Matte Finish over one of the leg pieces.  When I noticed an issue, I did a thin coat of the Testors Dullcote over the other leg.  Despite the problems...I did one more thin layer of Dullcote over the chest.  Here's where the issues started...

First issue!
Spoiler (click to show/hide)

Here's a close up...
Spoiler (click to show/hide)

I have no idea what's going on here.  It's almost as though the paint is shriveling up.  This was the Krylon Matte Finish.

Second issue!
Spoiler (click to show/hide)

While not as big of an issue, you can see the arm joint where the paint is already chipping.  That's from assembly alone.  This MAY be fixed with a gloss over the entire kit, but until I resolve the other issues, I'm not spraying ANYTHING on this kit. 

Slightly related, I noticed some parts were harder to snap together after painting.  Is this normal?  And if so, how does one remedy this?

Final issue!
Spoiler (click to show/hide)

So this REALLY sucks.  The first issue was Mega Man's left leg.  This, as you can see, is his right leg.  I used the Testors Dullcote for this one.

Can anyone give me some insight as to what's going on?  I refuse to assemble my other kits before figuring out the problem!   ???

A few things that might contribute to the problem.

1)  I live in the midwestern USA.  Indiana.  It's like, 30F outside right now.  I paint in my apartment in a spraybooth that blows outside.  It's about room temperature in here, but that ambient cool air COULD contribute.

2)  Tamiya Acrylics may use some funky formula that simply doesn't agree with Krylon or Testors coats.  If this is the case, I would LOVE a suggestion for a coat to use before/instead of these.

That's about all I can think of...Thanks guys!
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Piat

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Re: Finish coat problem
« Reply #1 on: January 08, 2013, 01:33:50 PM »

I am not sure on the paint reaction issue, but it looks like the top coat and the acrylics dont like each other at all.

The snap fitting this is because of the painting, as the parts have gotten thicker from the new layers. Best way to prevent this is to mask out the areas that will be fitting into another to prevent them thickening up.
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Hemish

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Re: Finish coat problem
« Reply #2 on: January 08, 2013, 01:57:00 PM »

Tamiya acrylics do no agree with testors top coats, use something else, I had that happen to one of my kits that I used testors on as well, after going back to mr top coat everything was peachy
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nicoga3000

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Re: Finish coat problem
« Reply #3 on: January 08, 2013, 02:09:56 PM »

Tamiya acrylics do no agree with testors top coats, use something else, I had that happen to one of my kits that I used testors on as well, after going back to mr top coat everything was peachy

I mean it in the nicest way, but I'm so glad this happened to you as well.  It makes me feel much better about the issue I've had.  

Can you use Mr. Top Coat + other coats for durability?  The second issue I'm having from the paint chipping off...Do you have that when you pose your kits/reassemble them?

E:  Also, after the Top Coat, can I still use the Testors Enamel wash for panel lining without ruining the kit?  Or, what's the better way to do panel lines via capillary action?
« Last Edit: January 08, 2013, 02:13:04 PM by nicoga3000 »
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Piat

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Re: Finish coat problem
« Reply #4 on: January 08, 2013, 02:13:06 PM »

Top coating should help prevent chipping and wear but I don't think there is any final solution to the problem if you pose and move the kits frequently, they will wear eventually, especially in jointed areas
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TheGhostofZeon

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Re: Finish coat problem
« Reply #5 on: January 08, 2013, 03:28:23 PM »

Tamiya acrylics are prone to scratches and chipping. In fact most acrylics are. If you want something more robust, I would try and enamel or a lacquer rather than an acrylic.

KaiK

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Re: Finish coat problem
« Reply #6 on: January 08, 2013, 04:41:35 PM »

It seems like the paint work wasn't entirely cured, the cold weather would have contributed to that. I'm not familiar with Krylon Matte Finish but from the MSDS it looks like it uses acetone as the primary solvent (~ 40% weight). Testors also has acetone (~10% weight) but uses alcohol as the primary solvent (~ 35- 40% weight).

The high amount of acetone in the Krylon is most likely the cause of your initial problem. Testors can be hit and miss when sprayed over Tamiya paints but in most cases it shouldn't react with fully cured paint. To ensure it doesn't make sure the can is well shaken, in cold weather partially submerge the can in warm water before spraying. Increasing the temperature of the can increases the output pressure and gives you a much more consistent finish.  

Top coat will give paint work a bit of scratch resistances but overall strength will come down to the type of primer and paint used. To me priming is a must, I use Mr Surfacer 1200 with an airbrush for most of my work. Tamiya also have a jar version of primer but it's often quite expensive for the amount given, it uses the same pot as Tamiya cement. For a long time now I've used Tamiya lacquer thinners with Tamiya acrylic paints. This increases the strength of the paint and decrease drying and curing time even in cold weather. For top coat I've used X-22 Clear and XF-86 Flat Clear along with the lacquer thinners with great results.

If you can get them I'd highly recommend using Mr Colour paints. They are solvent based acrylic paints which dry really strong and thin. Bandai manuals refer to the Mr Colour paint chart. The Super Clear range from Mr Colour is probably the strongest top coat I've encountered and can be found in the form of a spray can or pot. Alternatively there is Gaia paints which have the same attributes.  

Sprue Brothers stocks Mr Colour paints in the USA
http://store.spruebrothers.com/category_s/1978.htm
 
« Last Edit: January 09, 2013, 01:52:49 AM by KaiK »
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cobraleader

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Re: Finish coat problem
« Reply #7 on: January 08, 2013, 07:09:05 PM »

ouch ... not good ....

both Testors Dullcote (and gloss coat) and Tamiya Clear Coats are lacquers are "hot" paints - basically they will attack other types of paints unless there is a protective coat between them.

Try using Future (Pledge OneGo in Australia) before applying the lacquer coats... this may help protect the underlying paint.
Also try decanting the testors dullcote into a cup, thin it down the thinner and apply with an airbrush ....

Paint mediums are a pain in the rear end .... best applying Lacquers first, followed by enamels and then acrylics .... but it you have to use a different order (which is more normal for most of my models) apply some sort of protective clear coat between the lays .....

Lacquers aren't the only paints to attack acrylics, I've had an enamel wash eat through the acrylic paint as well......
some other effects you may experience is the testors dullcote will create a white finish when applied over acrylics .... really does mess with ya this stuff .... I've had successful use of Testors Dull and Gloss over acrylics, the one day they turned on me .... I now stick with the Future range to create clear finishes and if I want a dull finish (about 99% of the time) I'll apply Future (pledge one go) first then airbrush on Tamiya Flat Clear which has been decanted .....

A tip with Future, you can add an acrylic flat base to create a flat coat when applying it....
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nicoga3000

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Re: Finish coat problem
« Reply #8 on: January 08, 2013, 11:52:39 PM »

@KaiK - I have a few questions based on your method...

1)  When you thin with the lacquer thinner, how long do you wait for them to cure? 

2)  The X-22/XF-86 you use for top coats...Do they provide the same finish and protection as a Testors Dull or Gloss?  Can you do your enamel panel line wash over these without damaging the rest of the paint?

@cobraleader - regarding Future.  Can I apply Future (thinned with Isopropyl) for my top/seal coat, do my wash, and then use a Testors/Krylon top coat?  Or will that still cause problems?  From what I can find, Future is a water-soluble acyrlic, so that shouldn't have ANY adverse effects on Tamiya paints.  It looks like it will gloss the model, though.  I'd still prefer a dull finish (like you), but I'd like to avoid decanting sprays since I don't have a garage to do it in yet.

Thanks again for the valuable info everyone - this is definitely a fantastic learning experience for what I'm dealing with.  :)
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KaiK

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Re: Finish coat problem
« Reply #9 on: January 09, 2013, 02:27:19 AM »

Thinning Tamiya paints with lacquer thinner allows the paint to fully cure in around 2 hours depending on the mixture. I go with a 1:3 paint:thinner mixture at 15-20 psi.

Fully cured acrylic paint can become pretty strong however since Testors dull and gloss coats are lacquers they should be stronger, finish wise Testors dull coat has a really strong flat finish, Tamiya XF-86 Flat Clear doesn't create a deep flat finish but I find it creates a great finish none the less.

I built an Age FX (http://gundamaustralia.com/forum/index.php?topic=3440.0) using Tamiya Clear and Flat Clear for the top coat. The top coat was sprayed on bare plastic and has remained scratch resistant. It also shows that the Tamiya Clear has protected the surface from discolouration from and enamel wash, it actually makes it really easy to clean up washes.

Future can be thinned with 100% IPA, a 1:1 mixture works quite well. Future is extremely tough stuff and is quite good as a clear coat. Once dry you could spray just about anything on top without destroying the paintwork. If you've got future I wouldn't bother decanting a top coat spray can (I generally wouldn't decant a can at all), I'd just use Future mixed with Tamiya Flat Base.
« Last Edit: January 09, 2013, 02:28:21 AM by KaiK »
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cobraleader

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Re: Finish coat problem
« Reply #10 on: January 09, 2013, 11:47:28 AM »

the thing about the hobby is the diversity you see ... I find the decanting helps make the lacquer less aggressive and lets me have better contral applying with an airbrush.

since your practicing, try what we are all saying ...

I was like Kaik, applying straight from a can for finish coats, but found it was easy to pool the paint or miss areas ... so now I airbrush ....
I tend to use future (pledge one go) when ever i want to apply lacquer paint or add a wash or just to provide some protection just in case ... one thing i've noticed is that enamel and oil thinners dull future ... so i get a dull coat effect from the washes ...I don't have a fast and hard rule about when I use future .... i might get lazy and run the risk of ruining an acrylic finish ...

keep practicing ....
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KaiK

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Re: Finish coat problem
« Reply #11 on: January 09, 2013, 02:46:22 PM »

I don't use cans at all I find them too expensive in the long run. X-22 and XF-86 are pots.
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tristan

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Re: Finish coat problem
« Reply #12 on: January 09, 2013, 08:54:41 PM »

My 5 cents worth...dont use testors or krylon over tamiya. You should stick with all testers or all krylons as tamiyas can be testy buggers! I too live in a cold area (though not as cold as you) and have found tamiyas can be funny in cold weather when airbrushing.
For an overcoat, Ive found the gloss and matte sprays you get in art stores for use over drawings and photos work well but the tamiya clear coats should work the best. Since yo live in the States, you should try Future as everyone raves about it
http://www.swannysmodels.com/TheCompleteFuture.html
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nicoga3000

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Re: Finish coat problem
« Reply #13 on: January 09, 2013, 11:43:53 PM »

All this talk about Future had me picking up a bottle yesterday.  I also grabbed a bottle of Vallejo polyurethane gray primer and some Vallejo matte varnish that I can airbrush.  Those should be here by the end of the week.

I'll be sanding the legs and trying that out soon.  Thanks for the tips and info guys!
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dj898

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Re: Finish coat problem
« Reply #14 on: January 10, 2013, 03:28:18 PM »

Tamiya acrylics do no agree with testors top coats, use something else, I had that happen to one of my kits that I used testors on as well, after going back to mr top coat everything was peachy

Happened to me as well.
MG GM ver 1.5 conversion kit I did had the exact problem with the same combo.
Lesson learned... :(
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