Remove paint from aluminium aircraft

[Adrian Lewer]

Hi John. Been wondering how you have been going. Must get up and see you.

 

Yes please let me know the name of the product. I might use the parts I am replacing as a test bed for different tequniques and products after I have formed new parts from the old ( will make new parts as per plans but cross ref with the old ones)

 

come to think of it. Does anyone here have the skills to help me make a few parts off the plans such as a firewall ? Willing to help (actualy I want to) to learn a new skill but don't understand the whole plot method used for the firewall and ribbs.

 

I have a full set of plans here and might even consider building another complete airframe

 

when this one is flying. To build off plans is dirt cheap and YOU get to handle the quality.

 

 

[planedriver]

Adrian,We are in the process of repairing the skyfox. We found a product in Bunnings that isn't expensive, but removed each layer of paint one at the time. I am not sure of the name of it,but is in a yellow tin. I am off to Bunnings soon to find out the name of it. (any excuse to go to Bunnings). To clean it off the residue we used a spray bottle with metho in & a green scourer. John

Probably Polystrippa Adrian. Thats in a yellow can.

 

Wear gloves as it burns your skin if you get it on you, wash off thoroughly.

 

Many years ago I had a bit of a patch of corrosion on an outboard motor which kept re-appearing after painting. I had a chat with some guys at Bankstown who were repainting a Queenair. They gave me a couple of bottles of stuff to use which did the trick.

 

I still have the bottles but can't read what they wrote on them. The first one I think was called Dioxadin and the second one Alladin or something similar. Possibly chromic acid which I applied with a scotchbrite pad, then did the same with the second bottle and washed it all thoroughly before panting. It left a very finely scuffed finish which almost looked like it had been anodised pale yellow, and the fine scuffing act as a key and assists the new paint in gripping the aluminium surface.

 

I often seen aircraft around that are in the process of having a new paint job, and they all seem to have this yellowy finish before painting.

 

Might be worth a quick phone call to someone who specialises in it.

 

Hope this helps.

 

Kind Regards

 

Planey

 

 

[Guest Wigg]

Hi Adrian just got to paint the whole plane & put it back together. New prop arrived today so hope to get it finished soon. Cheers John

 

 

[Guest ozzie]

deoxidine is a 'acid' wash. basically removes any dirt and oxidation from the pore of the metal

 

Dealodine is a etch compound to seal it off and give a good 'key' for the primer.

 

I have some at home i'll give you the correct names and numbers for it when i get there tonight.

 

ozzie

 

 

[Guest ozzie]

The products i have are 'Henkel Surface Technologies' Alumiprep 33 this according to the label, deep cleans brightens and conditions, removes oxidation corrosion, chemically etches the aluminium surface, preps for painting, preps for welding.

 

Alodine 1201 for the chemical coating. 1201 is the gold/tan coloured used for under coloured paint. 1001 is the clear type if you are using under clear paint.

 

Alodine 1201 gives you a visible conversion coating, provides long lasting paint adhesion, protects against corrosion,

 

I've noticed over the years that serious builders of metal aircraft place the shiney surface of the skin on the inside. good time whilst you have this apart to give it some good internal anti corrosion treatment. paint it with zinc primer and treat it with ACF50 (bit like the endrust treatment for cars). Good investment if you are going to keep it and makes for better product for resale.

 

Keep posting your photos i am astounded on some of the work and amazed how it got signed off in the first place.

 

Ozzie

 

 

[planedriver]

The products i have are 'Henkel Surface Technologies' Alumiprep 33 this according to the label, deep cleans brightens and conditions, removes oxidation corrosion, chemically etches the aluminium surface, preps for painting, preps for welding.Alodine 1201 for the chemical coating. 1201 is the gold/tan coloured used for under coloured paint. 1001 is the clear type if you are using under clear paint.

Alodine 1201 gives you a visible conversion coating, provides long lasting paint adhesion, protects against corrosion,

 

I've noticed over the years that serious builders of metal aircraft place the shiney surface of the skin on the inside. good time whilst you have this apart to give it some good internal anti corrosion treatment. paint it with zinc primer and treat it with ACF50 (bit like the endrust treatment for cars). Good investment if you are going to keep it and makes for better product for resale.

 

Keep posting your photos i am astounded on some of the work and amazed how it got signed off in the first place.

 

Ozzie

You see guys, there's nearly always someone on these forums who has the right answers.

 

Thanks for that Ozzie, I learned something too.:thumb_up:

 

Rgds

 

Planey

 

 

[Adrian Lewer]

Ok Guy's I have downloaded the "How to Paint your own Aircraft" Book and It basically describes tequniques. Does not give descriptions on products used ETC.

 

From what I have gathered it is ok if I get water ANYWHERE within the airframe inside wings ETC but not to get paint stripper anywhere inside ?

 

What if I was to for arguments sake paint strip an aileron all over with out covering any holes up, then when it has done its job remove paint with scottchbrite and then hit it with the small gernie I have to remove the paint stripper from the cracks and from inside the aileron (if it found its way in) make sure I rinse it well so there is only water inside and outside of the aileron then let it dry up.

 

use the stuff to etch the aluminium and then paint ?

 

How does this sound ? will the water that has dried up inside the aileron or other parts effect it as long as I have removed all the paint stripper ?

 

My head is in a spin...

 

 

[Guest ozzie]

Best not to get any stripper inside. tape up all holes and seams as we discussed previously. the stripper is corrosive especially when it comes into contact with bare ali. when the surface is cleaned of paint almiprep wash then alodine wash prime and then paint. take your time and do it right in the prep this is the stage where it makes or breaks your finished product.

 

 

[Adrian Lewer]

Hi all, Went to see a friend today who is a Aircraft engineer and has every ticket under the sun, He has rebuilt aero commanders, pipers,cessna's, and lots more. This was his advice and he also showed me a Piper (or actually 3) he is rebuilding from the ground up at the moment.

 

Firstly use an aviation approved paint stripper as they do not create corrosion but are not as effective as automotive stuff. He has a complete Di Assembled tail of one of the pipers in this state. He said to go over it twice, completely rinsing the stripper off with a HOT water Gernie at high pressure.

 

At this stage you can leave them " AS IS " for a later date or continue on. If you decide to leave them you will need to paint strip one more time before moving on so he said just start when you are going to paint the lot.

 

after you have let the Panels totally dry you need to apply acidic detergent gel, (can't remember what this is for but he said it was important). this needs to be removed by hot water and the pressure washer.

 

After this you need to apply Alodine 1201 Which he said he buys crystals instead of a liquid based stuff. this is applied to the parts to be painted (just after they have air dried) via a spray bottle, gently rubbed in then allowed to sit for 10 or so minutes, then pour water over the surface and see if it beads or you get a film of water over the surface. you are looking for a film of water not a bead. once this is done pressure wash in hot water again and allow to air dry again.

 

then you need to use a urethane compatible primer (he uses PPG Paints)

 

at this stage you can store the parts without hassle just keep clean but he said just to paint them straight away.

 

Then onto a top coat which is a PPG Aircraft paint. aprox $1200 for 8 litres " OUCH "

 

he said you can use automotive paints for out up to 100 KTS aircraft as we don't see the harsh conditions and we are in VMC but if you fly in rain it will eventually kill leading edges.

 

I am hoping to help him to prep and paint the pipers and also help him re build another aero commander to gain some valuable experience.

 

Will keep you all posted on how I go.

 

 

[XAIRVTW]

Hi Adrian I am Spray Painter i not only paint cars I also do aircraft wether its a full re spray or just panels with blends.This is the procces I would follow, bare in mind I haven't seen your aircraft which would help make the decission on what I would do. This is the procces I would follow. If the paint is not craised or cracking or paint is not thick with layers I would not paint strip, I try not to use paint strip as it can cause some problems. 1) reaction with other surface bondings. 2) Bit of a mess to clean up eg-: around rivets & in creavies eg.

 

Sand the area to be paint with 240 grit paper feather out all egdes make sure surface is smooth,Prepsol down surface to be painted mask off any surface not to be painted, If using 2K (2 pac) makes sure anything you DONT WONT PAINTED IS COVERED this stuff floats in the air & sticks to anything, make sure you have a good mask & wear long sleeves or overall type clothing. Apply an etch primer which will seal aluminium surface similar to Alodine color build which is a primer allow to dry. Apply a guide coat if you have any grafite powder if not a lite spray of black paint not too heavy. Rub color build until guide coat has gone with 600 grit dry. You can use wet rub just make sure all water is clear of panel before painting you can use a flat block if you want surface to be flat.Clean surface with prepsol making sure all prepsol is wiped off re-mask if neccessary apply top coat allow to dry. Takes some practise you have to be able understand what the paint is doing when it leaves the gun eg-: is on to dry or to wet or am I keeping the paint even on the panel. Hope this helps .

 

Cheers tony

 

 

[HEON]

Although not up for a repaint I have found this very informative.

 

Seems to involve a lot of work. For interest, what would be an estimate of the weight added if not stripped LSA sided aircraft if repainting with (1) like colour (2) covering dark colour with a lighter one?

 

In otherwords is the effort worth it?

 

 

[Adrian Lewer]

Hi XAIRVTW,

 

The problem is you can't sand aluminium ? it is a big NO NO... The Paint on this A/C is laid on heavily hence the reason i would like to get rid of it all and start again. I think it is also Acrylic so my 2K job on the top will not like it, I have decided on going 2K for a number of reasons.

 

1. I have used it before

 

2. I am not going to operate outside VMC

 

3. I will not be flying in heavy rain constantly

 

4. Much cheaper than Aircraft Polyurethane's

 

After much Advice from My friend and others from here this is my plan of attack.

 

Use Applied Chemicals 8770 Paint stripper/de carboniser the surface to be treated.

 

with a scraper top to bottom scrape all paint from the part

 

from top to bottom use scotchbrite pads and scrub the part top to bottom with running water

 

once dried via air use Henkel Alumiprep 33 then use high pressure hot water to remove and once again air dry with compressed air.then treat with Henkel Alodine 1201 and once again hit with high pressure hot water and compress air dry.

 

I will then use Automotive 2K primer on the surface and repeat with all other surfaces to be completed.

 

Once all airframe parts are at a Primed stage I will start my Painting process and paint parts individually such as tail, elevator, ailerons, wing's, rudder fuselage and other various parts.

 

I will most likely paint in PPG auto.

 

 

[XAIRVTW]

Your not sanding aluminium you are sanding the paint with a very fine grade of paper the only thing you have too watch out for is the head of the rivets & that is done by hand. Painting it individually is the way to go. If the paint has several layers then I would strip it.If you have any fibreglass parts dont paint strip.

 

cheers Tony

 

 

[Guest Teenie2]

gee i hope u can sand aluminum , better ground every qantas aircraft and all military as well .

 

Yes u can sand alloy , just dont take much off , always do it in accordance with the aircraft maintenance manual.

 

 

[XAIRVTW]

Hi Heon yes there is a lot of prep work to do, attention to detail will give you a great finish. As far as weight you are not buiding layers up. Cheap 2k paint wont cover you need to spend some $$$ & buy quality product. The paint system I use allows me to cover a panel in with top coat in one coat saves time money & weight not cheap 500ml in solid color $180 metalic or pearl $250+

 

 

[Yenn]

If the paint is acrylic, try using metholated spirits to remove it. I have never done it but have heard that metho dissolves acrylic.

 

 

[Guest BOSStrip]

Paint Stripping

 

Has anyone tried sodablasting ?

 

 

[Guest ozzie]

There have been reports that dry ice/ soda blasting can change the temper of the aluminium. suggest some industry research into this method.

 

ozzie

 

 

[Thruster87]

The Catalina flying Boat wings were soda blasted and it took off about 80% of the previous coats of paint.Fine powder covered everything within 50m,so it is a bit messy and from memory a bit expensive.Paint stripper is the way to go, if you have a place to do it,so as not to upset the EPA. Cheers T87

 

 

[Robmus]

There is a company in Bannockburn and also a couple in geelong that use granulated soda to remove paint from delicate items. I am not sure of their Names but i am sure they would be in the phonebook. Hope this helps.

 

 

[Guest Maj Millard]

Adrian, I have done more aircraft paint stripping than I like to admit to, and often still do on a weekly basis in my current job with Air Whitsunday.

 

Most commonly used in the industry is a Turco product, yellow in colour, and you will need rubber gloves to use it, plus you'll know very quickly if you drop a spot on your leg !.

 

It's not as strong now as it used to be, (bloody greenies) so it generally takes two (or more) applications to get a good paint coat off. It works easier on flat sheet then say a wheel rim. I would not recommend using high pressure cleaners to wash it off, as you'll push it into unseen areas where if left, it'll cause corrosion. It is water soluable so hoses of ok with a standard hose. We often scrape off the blistered paint using a sharpe scraper made from 1/4" lexan which won't scrape the aluminum, like metal scrapers do. The Turco product is aircraft approved, and often stocked at most commercial paint product suppliers.

 

Although we do often bead-blast alum fittings (glass bead) I don't recommend beed-blasting flat alum skins as it work hardenes them, and can warp or stretch sheet alum rendering it useless for further use in aircraft.

 

It is not necessary to find or use MEK (Methyl Ethyl Ketone). Once you have remove the paint with paint stripper, green scourer and any good commercial solvent (gunwash, laquer thinners etc) will clean off the remaining paint residue most times.

 

 

[dazza 38]

Hi Ross, thats the same stuff we used in the RAAF, Turco.We used the same procedure as your mentioned above.

 

Also- If anybody needs MEK for any reason. - Plumbers primer/cleaner, is 100% MEK.You can buy it from plumbers suppliers.I use it everyday. It is carcinogenic after long term use. We used to use rags soaked in it, with bare hands to clean pipe and fittings. I now use a Brush to apply it.

 

 

[Guest ozzie]

Major next time you use that stripper (Paint) try wrapping the part in thick black plastic. i found it helps it work faster.

 

 

[Guest Maj Millard]

Ozzie, Yes that can speed things up a bit, but basically most of the paint strippers these days have been just watered down to what they used to be. As mentioned previously if the original paint is sound, and can be sanded to a suitable surface for repaint, thats the way to go in lue of the additional work (and mess) of paint-stripping.

 

Most of the modern 2-pack paints these days cover and stick really well, often with only one good coat.

 

Occasionally you will get one that doesn't get along with a certain primer coat, but most work well if everything is cleaned down with Prepsol prior to spraying.dazza...MEK by the way (carsinagenic in CA)) was the only approved cleaning fluid for nylon parachute canopies when I was in the airport, go figure !................Ross

 

 

[flyhi]

Sodablasting with bicarb soda is great for around rivet heads