Paint Stripping

PilotRPI

PilotRPI

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PilotRPI
I have to strip the paint off some old elevators. I was told to do the following:

  • Apply Aircraft Paint Remover and wait till it bubbles
  • Squeegee all the goopy paint off
  • Wipe down with papertowels and MEK
  • Repeat
Plus use maroon scotchbrite for any tough spots. Anything I'm missing there? I have the safety equipment I need.
 
I used this on the torque links on my plane prior to inspection. It takes a bit longer to bubble up but it is safe and worked really well.

HCG73803_CSStripGel_72dpi_300_300_80.jpg
 
PilotRPI said:
I have to strip the paint off some old elevators. I was told to do the following:

  • Apply Aircraft Paint Remover and wait till it bubbles
  • Squeegee all the goopy paint off
  • Wipe down with papertowels and MEK
  • Repeat
Plus use maroon scotchbrite for any tough spots. Anything I'm missing there? I have the safety equipment I need.
Click to expand...
Here is a better way. Use a good Epoxy Stripper, keep the stripper wet until all paint is loose, then apply a dish washing detergent and mix the stripper well with the soap. wash off. re-apply to stubborn areas.
DO NOT SCRATCH the aluminum surface.
Then etch with "aluminum-prep" and then re-"alidone".

Aluma-prep
http://www.aircraftspruce.com/catalog/cspages/metalprep.php?clickkey=12033
Alodine
http://www.aircraftspruce.com/catalog/cspages/alodine1201.php?clickkey=97301

Be certain to rinse all chemicals off the aluminum, and never touch the part with your bare hands, until painted.
Always wear eye protection and rubber gloves.
 
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When properly done, it will look like this.
 

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"Some old elevators", assuming they aren't fabric, and are metal. Do they have nonmetallic tips? Some strippers can ruin fiberglass or plastics.
 
172 elevators. Im going to let the mechanic prime and paint, i'll just do the dirty work of getting them down to metal.
 
Brush it on.....let it bubble.....power wash it off. Easy peasy....the old stuff was a pain...literally it burned. The new stuff is ammonia based and neutralizes on contact with water.
 
Laser is pretty amazing, but not cheap.
 
Checkout_my_Six said:
Brush it on.....let it bubble.....power wash it off. Easy peasy....the old stuff was a pain...literally it burned. The new stuff is ammonia based and neutralizes on contact with water.
Click to expand...
Yeah let's drive those acids into the rivet seams, we metal smiths love you for that.
 
GlennAB1 said:
Good one Tom, make sure you drive dissimilar metals together with your bead blaster.
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There ya go making the wrong assumption again..Where do ya get this ****? off your job cards?
 
GlennAB1 said:
Good one Tom, make sure you drive dissimilar metals together with your bead blaster.
Click to expand...
What does dissimilar metals have to do with chemical strippers.

Trying to creep the page again because you don't know the the subject?
 
Checkout_my_Six said:
it ain't acid....Tom. The new stuff ain't what you're use to.
Click to expand...
https://www.google.com/?gws_rd=ssl#q=ammonia+is+an+acid+or+base&*

The salts produced by the action of ammonia on acids are known as the ammonium salts and all contain the ammonium ion (NH4+). Although ammonia is well known as a weak base, it can also act as an extremely weak acid. It is a protic substance and is capable of formation of amides (which contain the NH2− ion).

Do you really want to leave that stuff in your rivet seams?
 
Tom-D said:
What does dissimilar metals have to do with chemical strippers.

Trying to creep the page again because you don't know the the subject?
Click to expand...
Uh Tom-

You are the one who called ammonia an acid. It is a base by the Brønsted–Lowry acid–base theory (accept hydrogen cations) or as an electron pair donor (Lewis base).

By calling ammonia an acid, you show you really don't know the subject.
 
Tom-D said:
https://www.google.com/?gws_rd=ssl#q=ammonia+is+an+acid+or+base&*

The salts produced by the action of ammonia on acids are known as the ammonium salts and all contain the ammonium ion (NH4+). Although ammonia is well known as a weak base, it can also act as an extremely weak acid. It is a protic substance and is capable of formation of amides (which contain the NH2− ion).

Do you really want to leave that stuff in your rivet seams?
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From your own reference again:
Ammonia is a typical weak base. Ammonia itself obviously doesn't contain hydroxide ions, but it reacts with water to produce ammonium ions and hydroxide ions. However, the reaction is reversible, and at any one time about 99% of the ammonia is still present as ammonia molecules.
Click to expand...
upload_2017-3-10_19-18-20.png
 
did you miss this?
"but it reacts with water to produce ammonium ions and hydroxide ions.""
read the whole link.. you'll find that ammonium is a electrolyte and that will cause corrosion when in contact with two dissimilar metals such as an Aluminum alloys used in the skins of our aircraft.
If you missed my point, I'll make it clear. You should not pressure wash the stripper off, it will drive stuff into the rivet seams that you do not want in there.
Most electrolytes are acids, the stronger the better in batteries, but any left in the seams (no matter how strong) of your aircraft are bad.
 
GlennAB1 said:
No, you told the world.
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wrong again,, you have no clue what I clean parts with or where. you were even surprised I got the color I did with Alodine, which tells me you don't have a clue how to clean parts for alodining. You've even admitted you use a solvent to clean the bare metal, Which means you don't know a etch from a solvent.
So until you know what the hell you are talking about reframe from adding confusion to the topic.
 
Tom-D said:
What does dissimilar metals have to do with chemical strippers.

Trying to creep the page again because you don't know the the subject?
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Tommy the twister... doesn't wanna see the similarity in "driving an acid into", and "driving a dissimilar metal into"
 
GlennAB1 said:
Tommy the twister... doesn't wanna see the similarity in "driving an acid into", and "driving a dissimilar metal into"
Click to expand...
Stay on subject and you won't require correcting.
 
Tom-D said:
did you miss this?
"but it reacts with water to produce ammonium ions and hydroxide ions.""
read the whole link.. you'll find that ammonium is a electrolyte and that will cause corrosion when in contact with two dissimilar metals such as an Aluminum alloys used in the skins of our aircraft.
If you missed my point, I'll make it clear. You should not pressure wash the stripper off, it will drive stuff into the rivet seams that you do not want in there.
Most electrolytes are acids, the stronger the better in batteries, but any left in the seams (no matter how strong) of your aircraft are bad.
Click to expand...

Tom- you just showed that ammonia is a base, not an acid, as you said here:
Tom-D said:
Yeah let's drive those acids into the rivet seams, we metal smiths love you for that.
Click to expand...

Seems you can't tell the difference between an acid or a base. You don't seem to know much chemistry in general, as you tend the spell the element abbreviated as Zn "zink"
https://www.pilotsofamerica.com/community/threads/corrosion.48898/page-2#post-896948

BTW, pretty much all water from the tap contains electrolytes- don't rinse your plane after washing it, Tom, if you are afraid of corrosion.
 
Tom-D said:
wrong again,, you have no clue what I clean parts with or where. you were even surprised I got the color I did with Alodine, which tells me you don't have a clue how to clean parts for alodining. You've even admitted you use a solvent to clean the bare metal, Which means you don't know a etch from a solvent.
So until you know what the hell you are talking about reframe from adding confusion to the topic.
Click to expand...
I know, you're confused enough. Solvent means oil to you. In my line of work we follow manufacturers instructions, we know you don't and even refer to boat school.

While we're at it, is the etch an acid or base?
 
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Cap'n Jack said:
no matter what it is, acid, electrolyte, or what, it isn't good trapped between the unprotected sheets of aluminum,

BTW, pretty much all water from the tap contains electrolytes- don't rinse your plane after washing it, Tom, if you are afraid of corrosion.
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nearly every thing is a electrolyte, in one variety or another, yes even water, but you still don't use a pressure washer to force it between the unprotected aluminum after stripping.

Your example of rinsing after washing isn't a good one unless you have a polished aircraft, otherwise the paint system should stop the water from entering the lap seams.

MY 170-B (2801C) I was required to replace 22 skins on that aircraft 4 years after it was stripped and pressure washed simply because it had this http://www.acehardware.com/product/..._clickid=1af27bd2-b81f-46fd-b1fc-7f9cbef1d9b5 Used on it and the citric acid forced into the seams by pressure washing.
 
Cap'n Jack said:
By calling ammonia an acid, you show you really don't know the subject.
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You are right I am not a chemist, But I am a Navy trained metalsmith that has been fighting and controlling corrosion in aircraft structures nearly all my life. I know what causes it, I know how to remove it, and I know how to treat it, But most of all I know how to prevent it.
And I didn't to know this stuff by looking it up on the internet, or reading a job card.
 
GlennAB1 said:
I know, you're confused enough. Solvent means oil to you. In my line of work we follow manufacturers instructions, we know you don't and even refer to boat school.

While we're at it, is the etch an acid or base?
Click to expand...
When your so called solvent creates a problem that you must rub and rub to get the golden hue that it supposed to show when alodine is applied. Then you state that you used schotbright to get it to color, simply tells any one with an ounce of intelligence that the solvent is an oil based one, Had it been an etch the alodine would have shown the proper color the instant it was applied.
Which proves you are either shooting the ships- about a subject you simply know nothing about, or you can't follow the directions on the alodine bottle.
 
GlennAB1 said:
Tommy the twister... doesn't wanna see the similarity in "driving an acid into", and "driving a dissimilar metal into"
Click to expand...
Have you ever read AC-43,13 ? chapter 6 ??Specially this part.
(2) Blasting.

(a) Abrasive blasting may be used on aluminum alloys using glass beads (Spec. MIL-G-9954) sizes 10 to 13, or grain abrasive (Spec. MIL-G-5634) types I and III may be used as an alternate method of removing cor- rosion from clad and non-clad aluminum al- loys. Abrasive blasting should not be used to remove heavy corrosion products. Direct pres- sure machines should have the nozzle pressure set at 30 to 40 psi for clad aluminum alloys and 40 to 45 psi for non-clad aluminum alloys. Engineering approval should be obtained prior to abrasive blasting metal thinner than 0.0625 inch.

(b) When using abrasive blasting on aluminum alloys, do not allow the blast stream to dwell on the same spot longer than 15 seconds. Longer dwell times will cause ex- cessive metal removal. Intergranular exfolia- tion corrosion is not to be removed by abrasive blasting; however, blasting may be used with powered corrosion removal to determine whether all exfoliation corrosion has been re- moved.

see anything there the FAA is worried about in corrosion removal by bead blasting, or the use of it on all metals in the same cabinet?

You really should stay in you little corner of the repair station and study to get your A&P.
 
You didn't notice that the instructions for abrasive blasting of different materials are contained in separate sections? ferrous is 6-116, aluminum is 6-136, magnesium in 6-152, titanium 6-181, copper 6-180, titanium 6-181.

Why doesn't it just have one reference for blasting metals?

Maybe you should read 6-2. a. Some factors which influence metal corrosion and rate of corrosion. (3) Presence of a dissimilar, less corridable metal.

And you need to be explicitly told blasting dissimilar metals with the same media is a bad idea?

Just look at aluminum alloys, it says to abrasive blast using glass beads. Does it say other metals can be used, even trace amounts that were transferred when blasting? No. Just glass beads.
 
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Tom-D said:
You are right I am not a chemist, But I am a Navy trained metalsmith that has been fighting and controlling corrosion in aircraft structures nearly all my life. I know what causes it, I know how to remove it, and I know how to treat it, But most of all I know how to prevent it.
And I didn't to know this stuff by looking it up on the internet, or reading a job card.
Click to expand...

Tom- I know you don't care what I, or anyone else thinks of you. However, you make yourself out to be a poor mechanic when you:
-Confuse acids and bases. This is taught in high school, nevermind the Navy
-Spell the element "zinc" as "zink"
-Pretend you know more than you actually do

If someone asked to to recommend a mechanic at Oak Harbor airport, I frankly, based on how you present yourself here, would tell them to avoid you at all costs.
Further, incidents such as that listed here don't help you at all:
https://www.ntsb.gov/investigations...ev_id=20150928X72825&ntsbno=WPR15FA268&akey=1
It was noted that there was black sealant applied to the crankcase halves mating surfaces, and there was no silk thread noted on the crankcase halve mating surfaces. It was also noted that the black sealant material was found in several of the oil galleys.
Click to expand...

Other people read these posts and discussions as well and they really don't reflect well on you.
 
One other thing, @Tom-D

Please don't change quotes on people. It is, at a minimum, extremely rude. It makes the person changing the quote appear to be a liar when they are caught. I didn't write the text highlighted below.
upload_2017-3-11_8-16-0.png


Here is an image of my original post- as can be seen, it is unedited so one can't claim that I changed the post to make you look bad
upload_2017-3-11_8-14-39.png
 
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