MIPA OC for aircraft paint

[tgmillso]

Hi All,

This question is probably more for those who are in the UK or Europe where MIPA paints are more common. I've been looking at my paint options, and a friend of mine who paints a lot of boats and other vehicles said he loved the way the Mipa paints laid down, with little orange peel or runs, and that he generally used almost half the paint to achieve the same finish. An attractive proposition if you are trying to save weight. I checked on the documentation from the manufacture and they seem to concur that this stuff can be applied more lightly than most polyurethanes (see page 4 of the document below).

http://www.mipa-paints.com/fileadmin/product/gb/product/prospekte/downloads/OC_GB.pdf

Anyway, I was interested if anyone had any experiance with it, it's durability and specifically what was your surface prep for the aluminium and fiberglass?
There is a local dealer for the paint here in town (another reason I've been investigating it as an option) and they are pulling together an application process for aircraft aluminium, which I should have shortly.

Cheers,

Tom.

 

[mike newall]

Our 7 is painted in MIPA.

I painted it in my shop - first experience of painting and it came out really well. The white will always be a challenge as it has a lot of pigment in and is difficult to spot when you are shooting too much.

Easy to mix and thin, I shot at 40psi from a 1.3mm nozzle in an HVLP gun.

As legislation encroaches, some of these paints get more difficult to obtain. My supplier switched from MIPA to Kapci which is very similar, I can't tell the difference.

Most of our 2k paint is now made in Beirut and Egypt ! Strange but I guess it gets around some law or other.

Drop me a line with an email address and I will send some snaps.

Mike

 

[tgmillso]

So I met the the Mipa store guys locally, and received the following process recommendation:
Clean with wax and grease remover, mechanical etch with maroon scotchbrite, clean again with wax and grease remover, apply 100micron (wet) of etch primer (resulting in a 10micron dry film), two hours later apply 1.5 coats of Mipa OC. Skip any clear coat.
Not long after that I received a response from their tech support in the head office. They were dead against applying directly over their etch, and recommended a high build in between, and perhaps even skipping the Mipa OC and using a medium solids paint instead, or even a basecoat/clear coat application.
So after all that confusion and contradiction, I went to the Wattyl (Valspar for those in the US) paint shop and got recommendation from them. Clean, mechanical etch with scotch brite, clean, 100 micron wet of etch primer, two coats of Colourthane C-Series polyurethane at 25 micron (dry) per coat. No top coat required unless it's going to be sitting outdoors 24/7 and you want better UV protection (less fading). Everyone and their documentation was in agreement with the process, so that's what I'm leaning toward at this stage. Although it's tempting to go down the high build primer path to fill rivets, I'm frankly not too concerned whether I can see the outline of a AN426 rivet and would rather save the time and weight and have the best possible adhesion of my top coat.
I worked out why the Mipa OC - standing for One Coat - looks so good in one pass, and it's because it's a super high solids content that they manage to somehow still make flow through a spray gun ok. Thus, although you only put on what seems like light coats, your total dry film thickness is still very high (and thus weight). Glad I worked this one out early.
On the spray gun side, I was still struggling to get something that met the specs of the compressors I have. I stumbled across LVLP (low volume low pressure) spray guns and read a few reviews and think it may be worth a try. There is this R500 model that seems to be sold under a few different banners, including Summit Racing LVLP, SprayIT SP-33000 and Asturo AOM-R500. I'll be getting plenty of practice with it before I shoot the real thing, so I will let you all know how it shoots.
Tom.

 

[mike newall]

Hi Tom,

Hope you got my email, if not get back in touch.

Gun - HVLP is much easier to use for a novice. Runs at 40psi at the tip, has great air and paint control, get a gravity fed one and practise on a wall panel to get a good balance of fan and paint delivery. As you change material, you may have to alter settings for different viscosities.

Usually, etch requires a build primer after it. The etch is protecting the substrate, the build primer is ready to accept the top coat chemistry.

Better to go for a 3 step etch, build top coat system than risk a high solids one coat and not get the finish you want.

 

[tgmillso]

Yes, thanks Mike, got your message. I just thought I'd share with the rest of the crew what I learnt. Re the top coat over the etch, this is what the paint manufacturer was recommending for aluminum, and is reflected in their application notes below. Keep in mind that his is for industrial applications, so they are recommending laying the etch down at 200 micron wet, but said I should aim for 100.
http://www.wattylindustrial.com.au/documents/industrial/Colouthane Metal Brochure.pdf
http://www.wattylindustrial.com.au/documents/industrial/tds/metal/Super Etch.pdf
I drilled them about laying the PU straight over the etch and they were quite adamant about it, to the extend that areas that I had already primed with Stewart systems Eko Poxy (such as the interior) should be cleaned, scuffed then shot with a light coat of etch before I apply the PU.
At the end of the day I've got my Van's toolbox to paint first, so I think I'll shoot this and see how the paint finish and adhesion works over the etch.
Re the gun, I only have a 2.2hp twin cylinder 9cfm at no load, 6.5cfm at 90psi with a 13 gal tank. I have another 2hp compressor I could even tee together, but that's still not even enough air to meet the cfm specs of most HVLP guns with a 1.3mm tip. Thus my plan is to try one of these LVLP guns as they are only $65, and if it works, great, and if I doesn't work, I'll go the LVLP route and rig up another compressor. I'm no too worried about my single compressor running continuously and getting hot as I'm running the air through a water cooling bath then water trap to pull the moisture out.
Tom.

 

[mike newall]

You won't have a problem with that compressor on an HVLP gun. Mine isn't much bigger and during a spray session, it hardly ever kicks in. You are shooting at 40psi at the tip.