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GregM

Removing paint and primer - The easy way for lazy folks!

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EDIT: Please see these post for the amazing results and how-tos:

About Methoxypropanol PM / Safety precautions: http://www.tamiyaclub.com/forum/index.php?showtopic=75942&p=581714

How to remove Tamiya primer: http://www.tamiyaclub.com/forum/index.php?showtopic=75942&p=581802

How to remove Tamiya paint / How to clean brushes: http://www.tamiyaclub.com/forum/index.php?showtopic=75942&p=582620




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ORIGINAL POST:


There's a static plastic model kit where I used Tamiya fine white primer. Unfortunately, I was a bit overenthusiastic when I applied it and the results are mold details being drowned in thick coats of primer.

Using oven cleaner as often recommended helps to get rid of the primer partially, and the plastic underneath is still very nice. But most of the primer still sticks so well in gaps even after two weeks of repeating the procedure daily, and I have no idea how I should go on. I tried using a tooth brush once, but won't do this again due to surface damage on the plastic caused by the brush.

I would really like to remove all the primer for a fresh start on the build. Your advice would be appreciated. :)

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I've used dot 4 brake fluid on Clod bodies before and it strips paint and primer without damaging the plastic.

It comes off in great big chunks, leaving nice clean plastic below. Maybe worth a try?

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I've had success using denatured alcohol (Methylated spirits in UK) to remove Tamiya acrylics from ABS bodies, but no idea if it works in the primer (but if it's the same base I'd assume it would).

Also great for cleaning brushes and my airbrush.

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Dettol will also remove tamiya primer, as well as most paints. (you need the antiseptic version, not the hand cleaner one).

I've found brake fluid can dry out the plastic, however I have noticed many people use it here without too many problems. I'd recommend trying out a small patch first.

Over cleaner can also work quite well. It needs to be sodium hydroxide based and make sure you wear gloves in a well ventilated area as the fumes are bad for you,

[edit] there is also de-solv-it, which I believe is an excellent paint remover, but I've yet to try it as it doesn't appear to be available in Australia [/edit]

regards

Johann

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Thank you so much for all of your suggestions. :)

I'll have a look around for the products you mentioned and see how they're called where I live. About the oven cleaner, I think mine could be one of the more aggressive ones, since there are toxic warning signs on the can. Yes, I wear gloves when doing the procedure, and keep the parts in a closeable container.

By the way, this is the kit I'm talking of:

http://www.tamiyaclub.com/forum/index.php?showtopic=74635&p=565905

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One of the chemicals in the tamiya primer is methylethylketone (MEK). The MEK's job is to burn into the polystrene and provide a "key" for the subsequent color to bond onto. Appart from the obvious abrasive methods which are fine for open surfaces, the chemical removal processes success will depend on how well it has keyed. If you are patient, a couple of weeks soaking in a solution of sodium hydroxide ( caustic soda ) can be rewarding.

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Greg as this is primer i have the nasty feeling that it will have keyed itself to the styrene so well that no matter what you try you will not manage to entirely remove it . Sanding may be your only option . .

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Yeah, I have that feeling, too. Some coats of primer have come off in chunks, but all the gaps are just painful to clean. Sanding is not an option unfortunately. If I can't get anywhere with the other methods mentioned, I might bite the bullet and order the YF-19 egg plane kit from Japan one more time. Good thing it wasn't too expensive, since it is a rather small scale one. It still annoys me that I was so impatient with priming, and I don't like to give in as long as I haven't tried everything I could to save the existing kit.

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Maybe in the long run it might be worth investing in a airbrush if your going to build these small scale kits ?

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Funny enough I was given an entry level airbrush set at birthday, so there's a good opportunity of getting some experience. It might be handy when I've got to do colours that aren't available as Tamiya rattle cans.

Next static kit I'd like to try would be a Tamiya 1/24 Ferrari Testarossa.

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I just ordered some Methoxypropanol PM. I've heard that it did wonders on plastic models primed and coloured with Tamiya paints as well as other paints. As far as I can see, it is also available as Dowanol PM, Solvenon PM, and Methyl Proxitol.

I'll let you guys and girls know if and how good it works on my model kit.

Additional information:

http://en.wikipedia.org/wiki/Propylene_glycol_methyl_ether_acetate

http://www.wettringer-modellbauforum.de/forum/index.php?page=Thread&threadID=19753

EDIT: Google translation for the forum link:

https://translate.google.de/translate?sl=de&tl=en&js=y&prev=_t&hl=de&ie=UTF-8&u=http%3A%2F%2Fwww.wettringer-modellbauforum.de%2Fforum%2Findex.php%3Fpage%3DThread%26threadID%3D19753&edit-text=

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Be careful with that stuff Greg . Please only use it outdoors as the fumes it gives off can soon become over powering .

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So I got 1 L of Methoxypropanol PM from Kremer Pigmente for Euro 7,27 + shipping.

Step 0: Wear gloves and eye protection. Open the window for good ventilation EDIT: GO OUTSIDE OF YOUR HOUSE. SERIOUSLY. That stuff isn't reeking as nasty as Tamiya X20A paint thinner, but well...

Then, I filled some of the liquid into a small jar. I use those 23ml Tamiya mixing jars, they are essentially empty X/XF paint jars. This way, I don't have to leave the large bottle open all the time.

I used a brush to apply the Methoxypropanol to primed and halfway painted parts. Then I left them in a closed tupper box for 15 minutes, and did the same procedure again. I can already see the primer and paint going thinner and even breaking down in some places on the large parts, mainly where the oven cleaner prep did it's job. Looks like this will work good, but needs some experimenting in applying to see how to get the best results on large parts.

Then I just threw all the small parts right into the 23ml jar, closed the lid firmly and shook the jar for about half a minute. Right before my eyes, I could see how the Methoxypropanol dissolved the primer with ease. I opened the jar, poured the content into box with the large main hull parts, took out the small parts and dryed them with a paper towel. I closed the box again with the large parts only and leftover liquid inside.

Amazing, all the paint and primer is gone from the small parts, leaving a nice clean surface. Even from the tiniest gaps. With next to no effort.

I'll see how I long it will take to get the primer off the large parts that can't be fully immersed in the liquid. Well, theoretically I could, but I don't want to waste the Methoxypropanol when it's not necessary to do so.

I'll also experiment with some scrap lexan and Tamiya polycarbonate paints. Carson Modelsport sells small bottles of Methoxypropanol under the name "Lexan Paint Killer", which did good results on my lexan M-03 Mini bodyshell before. If all goes well, this stuff has the potential to remove Tamiya paint and primer from both lexan and polystyrene bodyshells easily, without damaging or clouding the plastic itself.

EDIT: I will try the plastic bag method tomorrow for the main hull. Until then, I take these parts out of the box, since I do not want them to stay in contact with the liquid overnight.

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thanks for the update, I am looking forward to seeing how you go with the lexan parts. I've got several to do and have ruined one already.

I use the plastic bag method when I use dettol, making sure I take all the air out of the bag and then I place it in a big tub of water. It helps immensely to cut down on the amount of liquid you need.

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Aye, better safe than sorry.

:lol: at "aye" - are you maybe a Glaswegian at heart?!

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BEFORE:

th_WP_20141206_008_zpsdf023566.jpg th_WP_20141206_009_zps660c74ee.jpg

Bare plastic before priming.

th_SAM_3968_zpsf36xnrhm.jpg th_SAM_3969_zpsh9uxhshe.jpg th_WP_20150117_002_zpsaqqddglq.jpg

Primed. Please note the primer runs and orange peel.

AFTER:

So, I used the plastic bag method and let the Methoxypropanol react for 1 minute while shaking the closed bag carefully. Then I poured the leftover liquid into a glass jar.

th_WP_20150330_008_zpsn5n5z9nq.jpg

Primer removed (photo taken with flash to make primer residue more visible).

Pretty neat, isn't it? No rubbing, scratching or brushing involved.

My better half thinks Methoxypropanol smells awful. I think she's correct. Additionally, the fumes aren't very nice to the eyes, even though I left the window wide open.

So I strongly recommend to use Methoxypropanol only when you're outside in fresh air, even if it's freezing cold.

Keep it far away from your face all time.

Use gloves and get rid of them after use promptly.

Be careful what you touch with the gloves, as you may dissolve paint from other surfaces accidentally.

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Last weekend, I made a painting mistake. I used a dirty brush, which still had some black paint left within the bristle clamp. So the Hot Shot driver figure I started to paint got a rather unhealthy face colour.

Time for another paint removal!

Today, I opened the jar with the leftover used Methoxypropanol from the last paint/primer removal session and poured the content through a coffee filter into a small 23ml mixing jar. The filtered liquid was then applied with a brush to the driver's face. 1 minute later, I got the face clean and ready for new paint.

th_glups_zpsuzc9ofhv.jpg

Before - After

Looks like the white primer stayed on, but I'll spray another light coat on anyways to be safe.

I used the Methoxypropanol from the small mixing jar to give all my brushes a good clean. You won't believe how much paint pigments came out from that small darn 5/0 brush. :D Then, I used water to clean the chemicals off.

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Here's another one.

There is a garage kit made from resin cast that I originally assembled and painted on the Modelkit Universe workshop at the Animaco convention in Fall 2014.
It was primed with Motip primer and painted with water-based acrylic paints. The eyes are water-slide decals.
Yesterday, I decided I would like to redo the paintjob, thus the need for a paint removal.
th_SAM_4012_zpsxvomtmzk.jpg
The resin kit after disassembly.
th_SAM_4018_zpsazc3pq5g.jpg th_SAM_4024_zpsnivmeikc.jpg
The resin kit after paint removal.
Both paint and primer were easy to remove. In this case, it is recommended to remove most of the paint using a brush, and give the parts a bath in Methoxypropanol afterwards if necessary. On large flat areas, the paint will come down instantly, while wrinkled areas need a toothbrush to reach into all the gaps. The glue isn't affected at all, as well as underlying paint. These glued surfaces will need a sanding.

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