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Old Sep 20, 2012, 04:13 AM
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Litho-Plate Aging, Weathering

Hi

I'm looking for ideas on aging litho-plate (Aluminum sheet).

The plane I'm building is a Hawker Demon.
From looking at photos of a few Hawkers from that era, I notice variations in the color or sheen of the aluminum panels.

How to do this without loosing the natural "look" of the metal.

I've heard of 000 steel-wool used to take off a little shine. Maybe I was too aggressive in testing this technique as the results we unacceptable (to me),
Leaving it scratched up.

I know of "Blackeners" the M-Rail-Road guys use. This seems like a better solution as it leaves no imperfections on the piece.
Q: would vinegar or muriatic acid do the same thing ? (of course rinsing in a base afterwards)

Any Home-Brewed Weathering Solutions out there for Aluminum ?

Thanks.
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Old Sep 20, 2012, 10:08 AM
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maybe try alkali =caustic.. mild = baking soda, savage= caustic soda
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Old Sep 20, 2012, 01:27 PM
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Oven cleaner is a caustic material. Also some of your household cleaners might work. If it feels very "slippery" and when you rinse you fingers if it feels like you can't rinse it off, it is most likely a caustic product.

Ken

PS. Birchwood Casey make an aluminum blackening solution. It works very well. Just make sure there is NO oil on the surface, even from your fingers. The no oil goes for whatever solution you use.
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Old Sep 20, 2012, 05:16 PM
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Originally Posted by kenh3497 View Post
Oven cleaner is a caustic material. Also some of your household cleaners might work. If it feels very "slippery" and when you rinse you fingers if it feels like you can't rinse it off, it is most likely a caustic product.

Ken

PS. Birchwood Casey make an aluminum blackening solution. It works very well. Just make sure there is NO oil on the surface, even from your fingers. The no oil goes for whatever solution you use.
I will give the oven cleaner a test tonight The vinegar was a bust..
I'm looking for something that works rather quickly so I can control the amount of "dirtying up".
Maybe even Clear Sealer, Matt, Satin, would give a different look.

Update:
Muriatic Acid did not effect the aluminum. I'm sure it would "eventually" but not rapidly enough to control.
Gun Bluing solution also had no immediate effect. Used on bare steel the effects are instant
still waiting on the Oven Cleaner
Also waiting on Drain cleaner "Draino"
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Old Sep 21, 2012, 05:51 AM
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The Drain Cleaner (Draino) worked.

10 Minuets in the watered down drain cleaner has aged the Aluminum.
It turned it to a whitish grey.
Just like what would happen to a real Plane (I would imagine)

I was hoping for a darkening effect to better match the Paint Color of the rest of the Plane. Will have to investigate this Birtchwood Casey Solution.

Am going to try Pool Chlorine and see the results.

Saw a recipe for a Blackening Agent on the web, I am leery about mixing chemicals, as I'm no scientist, I wish to proceed with caution.
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Old Sep 21, 2012, 02:09 PM
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Quote:
Originally Posted by rockhound1218 View Post
The Drain Cleaner (Drano) worked.

10 Minuets in the watered down drain cleaner has aged the Aluminum.
It turned it to a whitish grey.
Just like what would happen to a real Plane (I would imagine)

I was hoping for a darkening effect to better match the Paint Color of the rest of the Plane. Will have to investigate this Birtchwood Casey Solution.

Am going to try Pool Chlorine and see the results.

Saw a recipe for a Blackening Agent on the web, I am leery about mixing chemicals, as I'm no scientist, I wish to proceed with caution.
The drain cleaner was probably acidic, hence the "white" color to the aluminum. You have to have an alkaline product or something more like the Birchwood Casey solution. The birchwood product will turn the aluminum absolutely black.

ken
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Old Sep 21, 2012, 11:58 PM
Jim C Patrick
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Drano drain cleaner is a caustic (alkaline) material. It has other ingredients like deodorizers, surfactants, etcetera; but the main ingredient is NaOH, known as lye or caustic soda. A strong lye solution on aluminum will generate intense heat and hydrogen gas; ie a fire or explosion waiting to happen. Lye burns cloth and flesh on contact and is highly poisonous. It reacts violently with many materials, including aluminum. Extreme caution should be used: thick rubber gloves, eye protection, rinse water available, etcetera.

A weak lye solution etches aluminum, producing a grainy finish that ranges from light to dark gray, and sometimes a iridescent rainbow shine. The strength of solution, temperature (!) and time of exposure make huge differences in the finish you get.

On the acid side, ferric chloride may work well. Radio Shack used to carry it for etching circuit boards and it is safer less dangerous than caustics.
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Old Sep 22, 2012, 05:17 AM
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"A weak lye solution etches aluminum, producing a grainy finish that ranges from light to dark gray, and sometimes a iridescent rainbow shine. The strength of solution, temperature (!) and time of exposure make huge differences in the finish you get."

This was the strength I used, it worked quickly(10-15 Min. soak) and the color was just ok. I used approximately 10 crystals Draino to 4 ounces water.

I know that More doesn't = Better ! Glad I stick to this motto.

I'm still searching up and down the PH Scale to find the right stuff.

Today I'll try some Pool Chlorine.
Regular table salt in a hot bath.
If those don't work I'll run them through the Dish Washer..... that always turns my Aluminum pan Darker Ha !

I belong to a Mineral Club, Science dudes there could recommend the the proper chemicals, mix it for me and give instruction on proper usage .
We meet once a month so I'll have to wait till next week.
I don't have the knowledge to mix chemicals on my own. I know of certain mixtures that are deadly poisonous or burst into flames ! So I leave that to the experts. If I need to wear a gas mask or flame retardant clothing all for "Aged Aluminum" , I don't want it !
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Old Sep 23, 2012, 12:17 PM
Jim C Patrick
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As I understand it —correct me if this is not what you intend— the finish you want is weathered aluminum. This is normally a flat light-gray or off-white metallic look. This is caused by 'deep' oxidation of the aluminum.

Aluminum always has an oxide layer, but on fresh cuts or new aluminum the oxide layer is all-but invisible. You could try adding some hydrogen peroxide from the drugstore into your existing weak lye solution. Another way is to simply put the aluminum sheets in some water outside and leave them in it a few weeks, moving them every so often to keep the oxidation even. If perfect authenticity is your goal, then chemically 'aging' the aluminum is what you have to do.

But . . . for a model it seems to me like you are trying to do this the hard way. An airbrush —yours or a friends— with matte clearcoat and a touch of very light gray mixed in it would get the job done in a few minutes, and dry in an hour. The aluminum color and sheen would still show through, but have the added 'oxidation' from the paint.
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Old Sep 23, 2012, 02:35 PM
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To me , Nothing looks more like metal than metal ... If I had to prime the Aluminum (paint wont last without priming) , color each individual panel to give variations. ect. seems like a lot of work !
Much easier to Dunk the Entire Panels 12"x 15" into "solutions of different strengths, before I even make the parts.
I get variation I need and the weathering in one shot.
If needed your method could be used to blend everything together at the end. More likely...
to cover up my screwups. and go From Scale to Stand way Off.

It may seem to some to be the hard way,
but to me, it seems like the right way.
If the Plane had Painted Panels ...I'd paint them.
If it was just a Model , I wouldn't bother building it from scratch, I'd buy (gulp) an ARF .... kidding

Half the fun of building (for Me) is learning new techniques to achieve the desired results. I'm not in a hurry or pressed to get things done. It's such a relaxing hobby, it takes me about two years to build a Flying Scale Model.

Am going to test the Hydrogen Peroxide ...
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Old Sep 23, 2012, 03:25 PM
Jim C Patrick
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Quote:
Originally Posted by rockhound1218
If it was just a Model , I wouldn't bother building it from scratch, I'd buy (gulp) an ARF .... kidding. Half the fun of building (for Me) is learning new techniques to achieve the desired results.
To each their own. My better half laughs about me 'building something for a few months just to crash it in a few minutes'. Sadly there is way too much truth in it. ;-)

Another technique to age aluminum is vinegar with salt; and an unusual method is covering with olive oil and heating to the point the the oil turns brown. You could buy Aluminum Black for $10 and dilute it a little. Sodium carbonate (washing soda or soda ash) is at most large grocery stores in with the clothes detergents; it works similar to lye but is safer, slower and more controllable.

Probably the drain cleaner, oven cleaner or lye is the cheapest and fastest way to get the finish you want; look for the sodium hydroxide as an ingredient. And at least one professional metal finisher recommends adding dissolved salt to the weak lye solution.
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Old Sep 23, 2012, 04:40 PM
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Ha She's right ...

I haven't flown a plane since the 70's C\l or Combat
I've been scratch building since then , scale models that I would\could never fly.
I'm lucky to know a pretty good pilot and He gets to Fly them.
All these years and maidens No wonder his hair turned grey.

This coming year it's my time to try my hand at flying R\C.
I listened to him and bought a Kit. and a few rolls of Mono Coat.
First Kit in 40 years. It's tough to go backwards But I don't want to wreck my good stuff.

Nice info on the "solutions" I tried Vinegar but not with Salt, will try.
Maybe add the Salt slowly after the panel is in the Vinegar, hoping for a "mottled"effect.
Soda Ash..... Slow and Controllable , sounds perfect.

I may do a sheet and over cook it with the Drano, some panels on my "docs" show deep pitting around the engine cowl.
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Old Sep 23, 2012, 09:40 PM
The Prez....... again
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Quote:
Originally Posted by rockhound1218 View Post
"
So I leave that to the experts.
A former work mate who is supposedly an "expert", once (he and I worked in the commercial laundry industry) dumped a competitors bleach down the drain followed buy an acidic product. That combination makes chlorine gas. He cleared out the bottom floor of the hospital where he was at

So even "experts" make mistakes.

My definition of "expert is as follows;

An "EX" is a has been.
A "SPERT" is a drip under pressure.
So an expert is a "Has been drip under pressure".

Yup a bit off topic, sorry

Ken
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Old Sep 25, 2012, 09:05 AM
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A little levity is always good to break up the monotony.
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Old Oct 30, 2012, 10:02 PM
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Here's what a little muratic acid did for my pop can aluminum framed canopy. What I do is sand the aluminum first , leave the sanding residue and just pour straight acid onto the part and leave it for a few minutes , then rinse off then scuff a little with steel wool .
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