A Brewster Buffalo found in the waters off Midway

[airnutz]

Isn't this a crash site reasonably well-known to divers, and that the only person who has "discovered" it is the journalist who wrote the recent article?

Like the Otay Helldiver, it was KNOWN to be there somewhere unless an earlier previously undocumented salvage had occured. The last independant dive looking for it was about 2000(IIRC) before the atoll came under the control of the National Park service. I believe there was a U of Hawaii attempt shortly after, but no luck. Check out the Dan Ford' site. Also Chris Brames link to the earlier WIX discussion will connect you to 3 threads, but I'm pretty sure there are at least one or 2 more. Rob, for some reason kept starting separate threads rather than keeping it all in one place.

Last edited by airnutz on Sun Jan 13, 2013 8:21 am, edited 1 time in total.

[Noha307]

Something submerged in saltwater would have to be completely washed down with freshwater and then submerged once again in fresh water (S.S. Hunley for example) for an extended length of time.

You mean C.S.S. Hunley. (C is for Commemorative )

[Stephan Wilkinson]

Something submerged in saltwater would have to be completely washed down with freshwater and then submerged once again in fresh water (S.S. Hunley for example) for an extended length of time.

Actually, it's considerably more complex. The freshwater-bath technique does far less good than has been assumed, and the process should involve (I think--typing from memory here...) a citric-acid bath. The University of Texas has done extensive research on the problem of saltwater immersion and has developed some useful processes.

[cooper9411]

I understand it is more complex. For time and space I was giving a "jist" of how it has been performed in the past. Thanks for the current info though.

[Noha307]

Something submerged in saltwater would have to be completely washed down with freshwater and then submerged once again in fresh water (S.S. Hunley for example) for an extended length of time.

Actually, it's considerably more complex. The freshwater-bath technique does far less good than has been assumed, and the process should involve (I think--typing from memory here...) a citric-acid bath. The University of Texas has done extensive research on the problem of saltwater immersion and has developed some useful processes.

If anyone else is wondering, it involves electrolysis, the same process modern submarines use to make oxygen. The problem is that salt makes its way into the metal. This does not cause much of a problem on the ocean floor, but as soon as the metal is raised it starts to dry out and the salt crystals expand, essentially breaking it apart from the inside. My understanding is this process is similar to what happens when water makes its way into cracks in cement in the sidewalk and then expands when it freezes. What electrolysis does, is remove the salt from the metal.

Please note, that all the information in this post pertains to iron, I have NO idea if the same principles apply to aluminum. I would also like to point out that I am not an expert on this, so take my information with a grain of salt. (Yep, you can kill me for that pun. )

If you want to listen to some real experts, the CSS Hunley's website, as well as the USS Monitor's, have excellent descriptions of the process:

• Conservation - Friends of the Hunley
• The Conservation Process - The Mariners' Museum
• Countering the Effects of Corrosion - The Mariners' Museum

[JFS61]

Actually, it's not the formation of crystals from the salt water that causes the corrosion, it's the chlorides from the salt water. When exposed to the atmosphere, they combine with hydrogen to form hydrochloric acid (HCL) which in turn dissolves the metal from the inside out. More noble metals such as gold are immune to this, but as many people have found out the hard way, a less noble metal such as aluminum isn't.

Everything you wanted to know about conservation of underwater artifacts (and more) can be found here:

http://nautarch.tamu.edu/CRL/conservati ... /File1.htm

Last edited by JFS61 on Wed Jan 09, 2013 11:50 pm, edited 1 time in total.

[Noha307]

Actually, it's not the formation of crystals from the salt water that causes the corrosion, it's the chlorides from the salt water. When exposed to the atmosphere, they combine with hydrogen to form hydrochloric acid (HCL) which in turn dissolves the metal from the inside out. More noble metals such as gold are immune to this, but as many people have found out the hard way, a less noble metal such as aluminum isn't.

After reviewing the links I posted I indeed noted that you are correct that it's the chlorides, not the salt itself. I am also glad someone was able to confirm that aluminum is susceptible to the same problems as iron. However, I am still a bit confused, but less so than when I began writing this post. The problem is the websites in the links confirm the understanding I posted about the crystals expanding and pushing the metal apart. The short version is I think we are both more or less correct. The long version is that I think two different processes are being discussed here and we (or maybe just I) have been assuming there is only one. The process of deterioration I was describing does not technically involve corrosion. The process you are describing does technically involve corrosion. Both processes, however, involve deterioration of the metal. The confusion arises because both processes involve some form of chemical reaction and both involve salt in some way. However, in the process I described the chemical reaction only facilitates the deterioration, that is to say the actual deterioration of the metal is entirely through physical forces, or put more simply, pushed apart. In the process you described the chemical reaction actually causes the deterioration itself, with the metal being dissolved by the acid.

Please feel free to rebut my conclusion, it is based on my analysis alone and not supported by anything other than my observations, understanding and logic regarding the situation. (Actually, I'm no longer so sure that the process I described involves a chemical reaction, but I'm too lazy, busy and tired to rewrite the paragraph.)

I hope that wasn't too confuzzling.

[JFS61]

Actually, it's not the formation of crystals from the salt water that causes the corrosion, it's the chlorides from the salt water. When exposed to the atmosphere, they combine with hydrogen to form hydrochloric acid (HCL) which in turn dissolves the metal from the inside out. More noble metals such as gold are immune to this, but as many people have found out the hard way, a less noble metal such as aluminum isn't.

After reviewing the links I posted I indeed noted that you are correct that it's the chlorides, not the salt itself. I am also glad someone was able to confirm that aluminum is susceptible to the same problems as iron. However, I am still a bit confused, but less so than when I began writing this post. The problem is the websites in the links confirm the understanding I posted about the crystals expanding and pushing the metal apart. The short version is I think we are both more or less correct. The long version is that I think two different processes are being discussed here and we (or maybe just I) have been assuming there is only one. The process of deterioration I was describing does not technically involve corrosion. The process you are describing does technically involve corrosion. Both processes, however, involve deterioration of the metal. The confusion arises because both processes involve some form of chemical reaction and both involve salt in some way. However, in the process I described the chemical reaction only facilitates the deterioration, that is to say the actual deterioration of the metal is entirely through physical forces, or put more simply, pushed apart. In the process you described the chemical reaction actually causes the deterioration itself, with the metal being dissolved by the acid.

Please feel free to rebut my conclusion, it is based on my analysis alone and not supported by anything other than my observations, understanding and logic regarding the situation. (Actually, I'm no longer so sure that the process I described involves a chemical reaction, but I'm too lazy, busy and tired to rewrite the paragraph.)

I hope that wasn't too confuzzling.

That's why I posted the link to Texas A&M Nautical Archaeology Conservation Lab, probably the leaders in underwater artifact conservation (According to TIGHAR, they supposedly once consulted with them regarding conservation strategies for the Jaluit Devastators), as it is indeed a complex process. I wish I remembered more, but it's been over 20 years since I took their conservation classes, and my memory has faded a bit with time (not to mention that chemistry was never my strongest suit, anyway, much to the dismay of my father who has a PhD in Chemical Oceanography). Even though I didn't pursue it any further, it was pretty fascinating stuff nonetheless.

[Stephan Wilkinson]

the link to Texas A&M Nautical Archaeology Conservation Lab...

You're absolutely right. When I posted (above) that the pioneering work had been done by "the University of Texas," I meant--or should have meant--Texas A&M.

[HawkerTempestMKII]

Interesting points.

I would think if there was a possibility to put the plane in a tank and experimentally show that the corossion process can be reversed, then a shipboard tank could be developed and used for salvage purposes. At least a temporary tank could be used until the plane can be placed in the "corrosion reversal" tank and salvaged. I am sure if the process could be developed somebody could turn the whole thing into a high profile media recovery event with investors like the Spitfire recoveries in Burma.

[bombadier29]

Interesting points.

I would think if there was a possibility to put the plane in a tank and experimentally show that the corossion process can be reversed, then a shipboard tank could be developed and used for salvage purposes. At least a temporary tank could be used until the plane can be placed in the "corrosion reversal" tank and salvaged. I am sure if the process could be developed somebody could turn the whole thing into a high profile media recovery event with investors like the Spitfire recoveries in Burma.

Except the plane belongs to the Navy. So none of that will ever happen most likely.

[HawkerTempestMKII]

Not this plane in particular. Any plane in general Army, JapaneseGerman, British, etc.

[airnutz]

the link to Texas A&M Nautical Archaeology Conservation Lab...

You're absolutely right. When I posted (above) that the pioneering work had been done by "the University of Texas," I meant--or should have meant--Texas A&M.

Get a rope! You've just guaranteed yourself a place at the next "hemp necktie party" thrown by either of those fine institutions!

[airnutz]

Where's the Buff? Are those patches of blue sheet metal barely exposed in the sand under the engine and landing gear chunks in the following photos? Plenty of steel bits, but I hope they can show us more ...or at least some, aluminium in the future.
Clic on picks for larger detail...
http://www.papahanaumokuakea.gov/mariti ... ffalo.html

More pics, clic on 'em for Hi-Rez....
http://www.papahanaumokuakea.gov/mariti ... hotos.html