Hi there. I bought a bunch of big aluminum screws to help secure an aluminum pergola I'm building (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll probably anodize the screws). I Googled it and found a couple tutorials around using citric acid and another using another type of acid. However, when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong enough acid) ? Thanks!

On Wednesday, October 18, 2017 at 7:44:04 AM UTC-4, Arjun Sharma wrote:
Hi there. I bought a bunch of big aluminum screws to help secure an aluminum pergola I'm building (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll probably anodize the screws). I Googled it and found a couple tutorials around using citric acid and another using another type of acid. However, when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong enough acid) ? Thanks!

Tractor Supply Co sells Citric acid. It is used by farmers to clean milking machines and such.

But why remove the zinc plating. It is there to reduce galvanic corrosion.

Dan

"Arjun Sharma" wrote in message
...
Hi there. I bought a bunch of big aluminum screws to help secure an aluminum
pergola I'm building
(https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll
probably anodize the screws). I Googled it and found a couple tutorials
around using citric acid and another using another type of acid. However,
when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong
enough acid) ? Thanks!

I think you have a bigger problem. I don't think you have aluminum screws.
I have never heard of aluminum lag screws (it seems like an extremely poor
application for aluminum) and can see no good reason why they would be zinc
plated (I am not sure it is even possible).
I can see a good reason why normal steel lag screws would be zinc plated.
When I search for the part number, sku, or upc code, it comes up as Zinc
Plated Steel Grade 2 everywhere except the amazon page.

On Wed, 18 Oct 2017 09:16:32 -0500
"Paul K. Dickman" wrote:

"Arjun Sharma" wrote in message
...
Hi there. I bought a bunch of big aluminum screws to help secure an aluminum
pergola I'm building
(https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll
probably anodize the screws). I Googled it and found a couple tutorials
around using citric acid and another using another type of acid. However,
when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong
enough acid) ? Thanks!

I think you have a bigger problem. I don't think you have aluminum screws.
I have never heard of aluminum lag screws (it seems like an extremely poor
application for aluminum) and can see no good reason why they would be zinc
plated (I am not sure it is even possible).
I can see a good reason why normal steel lag screws would be zinc plated.
When I search for the part number, sku, or upc code, it comes up as Zinc
Plated Steel Grade 2 everywhere except the amazon page.

I think someone goofed when they were writing the specs. If you look a
bit farther down the page:

"Product description

Zinc Plated Steel Grade 2 - Manufacturer: Hodell-Natco Industries."

I've got some small aluminum wood screws that were used to fasten my
storm windows to the trim. They are maybe a #8 and 1/2 inch long. It
doesn't take a lot of torque to twist the head off with a slotted
screwdriver...

I would use some Anti-seize like:

https://www.amazon.com/Dynatex-49550...dp/B009XE8AEM/

https://www.amazon.com/dp/B000FW7VGE/

generously on the threads or a thick grease, like wheel bearing. I've
had good results through the years using either of them...

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

On Wed, 18 Oct 2017 09:16:32 -0500, "Paul K. Dickman"
wrote:


"Arjun Sharma" wrote in message
...
Hi there. I bought a bunch of big aluminum screws to help secure an aluminum
pergola I'm building
(https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll
probably anodize the screws). I Googled it and found a couple tutorials
around using citric acid and another using another type of acid. However,
when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong
enough acid) ? Thanks!

I think you have a bigger problem. I don't think you have aluminum screws.
I have never heard of aluminum lag screws (it seems like an extremely poor
application for aluminum) and can see no good reason why they would be zinc
plated (I am not sure it is even possible).
I can see a good reason why normal steel lag screws would be zinc plated.
When I search for the part number, sku, or upc code, it comes up as Zinc
Plated Steel Grade 2 everywhere except the amazon page.

Yeah, if that screw is aluminum, it looks like it would twist right
off. Something isn't right there.

FWIW, though, galvanized platings are sometimes used to protect
aluminum. The galvanic potential of the two metals is close but the
zinc would still corrode preferentially. It is used in some marine
environments.

Stripping it off would be a mistake in any case. Any galvanic
corrosion would attack the zinc and protect the aluminum. Ordinary
muriatic acid (dilute hydrochloric) is what I use to strip galvanizing
off of steel EMT tubing for brazing or welding, but it will also
attack aluminum.

--
Ed Huntress

On Wednesday, October 18, 2017 at 6:44:04 AM UTC-5, Arjun Sharma wrote:
Hi there. I bought a bunch of big aluminum screws to help secure an aluminum pergola I'm building (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll probably anodize the screws). I Googled it and found a couple tutorials around using citric acid and another using another type of acid. However, when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong enough acid) ? Thanks!

Thanks for the input, everyone.

Any idea what people use, then? I know pergolas (and other structures) made from aluminum are quite common. Surely they have some mechanism for attaching the aluminum to the ground, wall, or in my case parapet wall.

I don't mind just using these screws, assuming they're zinc-plated steel. I just was worried about galvanic corrosion over time.

On Wed, 18 Oct 2017 16:41:10 -0700 (PDT), Arjun Sharma
wrote:

On Wednesday, October 18, 2017 at 6:44:04 AM UTC-5, Arjun Sharma wrote:
Hi there. I bought a bunch of big aluminum screws to help secure an aluminum pergola I'm building (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll probably anodize the screws). I Googled it and found a couple tutorials around using citric acid and another using another type of acid. However, when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong enough acid) ? Thanks!

Thanks for the input, everyone.

Any idea what people use, then? I know pergolas (and other structures) made from aluminum are quite common. Surely they have some mechanism for attaching the aluminum to the ground, wall, or in my case parapet wall.

I don't mind just using these screws, assuming they're zinc-plated steel. I just was worried about galvanic corrosion over time.

Depends on where you live if you need to worry about galvanic
corrosion.

I live in the high desert of central California. Things take multiple
decades to rust.

65 miles away..on the shores of the Pacific..it takes weeks.

You can always buy stainless steel screws and use them.


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

On 10/18/2017 6:18 PM, Gunner Asch wrote:
On Wed, 18 Oct 2017 16:41:10 -0700 (PDT), Arjun Sharma
wrote:

On Wednesday, October 18, 2017 at 6:44:04 AM UTC-5, Arjun Sharma wrote:
Hi there. I bought a bunch of big aluminum screws to help secure an aluminum pergola I'm building (https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll probably anodize the screws). I Googled it and found a couple tutorials around using citric acid and another using another type of acid. However, when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a strong enough acid) ? Thanks!

Thanks for the input, everyone.

Any idea what people use, then? I know pergolas (and other structures) made from aluminum are quite common. Surely they have some mechanism for attaching the aluminum to the ground, wall, or in my case parapet wall.

I don't mind just using these screws, assuming they're zinc-plated steel. I just was worried about galvanic corrosion over time.

Depends on where you live if you need to worry about galvanic
corrosion.

I live in the high desert of central California.

Bull****. I have shown repeatedly that your dump is at about 1025'.
There's a topo map that shows the 1025' contour running literally right
through your dump.

http://www.topoquest.com/map.php?lat...=zoomin&size=m
or http://tinyurl.com/7e6cgvq

The street running right below the words "South Taft" (synonymous with
"Giant meth lab") is Wood Street. The red and white striped line
running between the words is Olive Av. You live on the east side of
Olive, two shacks above Wood. The dark brown line running through the
letters 'ft' in 'Taft' is the 1000' elevation line. The next dark brown
line to the southwest of that line, running just above "Conley School"
and through the red number "24", is the 1100' line. The intermediate
lines mark 25 feet of elevation gain.

As we can plainly see, the 1025' line runs directly through your shack.
Your claim to live at 1953' is bull****. But everyone already knew that.

The high desert starts at 2000' elevation. Your elevation is a bit over
half that. You do not live in the high desert of central California -
there isn't any such high desert.

"Arjun Sharma" wrote in message
...
On Wednesday, October 18, 2017 at 6:44:04 AM UTC-5, Arjun Sharma wrote:
Hi there. I bought a bunch of big aluminum screws to help secure an
aluminum pergola I'm building
(https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll
probably anodize the screws). I Googled it and found a couple tutorials
around using citric acid and another using another type of acid. However,
when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a
strong enough acid) ? Thanks!

Thanks for the input, everyone.

Any idea what people use, then? I know pergolas (and other structures) made
from aluminum are quite common. Surely they have some mechanism for
attaching the aluminum to the ground, wall, or in my case parapet wall.

I don't mind just using these screws, assuming they're zinc-plated steel. I
just was worried about galvanic corrosion over time.

You could electrically isolate the bolts by using a plastic sleeve and
washer to keep the steel screw from actually touching the aluminum.

On Thu, 19 Oct 2017 08:17:50 -0500, "Paul K. Dickman"
wrote:


"Arjun Sharma" wrote in message
...
On Wednesday, October 18, 2017 at 6:44:04 AM UTC-5, Arjun Sharma wrote:
Hi there. I bought a bunch of big aluminum screws to help secure an
aluminum pergola I'm building
(https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1)

I'd like to remove the zinc plating to reduce galvanic corrosion (I'll
probably anodize the screws). I Googled it and found a couple tutorials
around using citric acid and another using another type of acid. However,
when I went to the hardware store, they had nothing of the sort.

Any suggestions for the best way to go about this (or where to get a
strong enough acid) ? Thanks!

Thanks for the input, everyone.

Any idea what people use, then? I know pergolas (and other structures) made
from aluminum are quite common. Surely they have some mechanism for
attaching the aluminum to the ground, wall, or in my case parapet wall.

I don't mind just using these screws, assuming they're zinc-plated steel. I
just was worried about galvanic corrosion over time.

You could electrically isolate the bolts by using a plastic sleeve and
washer to keep the steel screw from actually touching the aluminum.

Right. Unless you isolate them like that, either the fastener or the
abluminum being fastened is going to corrode eventually. In the case
of common steel fasteners, they'll corrode first -- and it's generally
simple oxidation of the steel, not galvanic corrosion in the presence
of aluminum in a galvanic "cell." Theoretically, the aluminum should
protect the steel but it usually does not.

Google "fasteners for aluminum" and read a few of the explanations.
You'll see what's used in industry, and why, with plenty of examples.

--
Ed Huntress