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On Topic: Choice of paint used inside S-I stage
On Tue, 29 Apr 2008 00:22:18 -0500, Damon Hill
wrote: Well, from what I've seen of the salt haze down there, some daze it's so thick that everything more than a few miles away turns the same greyscale and blends together. ....The Texas Gulf Coast can be just as bad if the conditions are just right. Last time Dim and I went down there to see the Confederate Air Force Museum, it was bright and sunny overhead, but if you looked out Gulfward, visibility was about two miles before everything disappeared in a thick grey haze. And this was just before noontime, too, and the salt was thicker in the air than I can recall. Which, for once, helped mask the stench of seagull droppings that usually permeates the air to halfway intolerable levels. OM -- ]=====================================[ ] OMBlog - http://www.io.com/~o_m/omworld [ ] Let's face it: Sometimes you *need* [ ] an obnoxious opinion in your day! [ ]=====================================[ |
#12
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On Topic: Choice of paint used inside S-I stage
On Tue, 29 Apr 2008 00:22:18 -0500, Damon Hill
wrote: OM wrote in : On Mon, 28 Apr 2008 22:20:52 -0500, Damon Hill wrote: Yellow chromate primer to prevent corrosion of the aluminum? ...This makes sense, as the primer used on a lot of nautical items is the same type. It does beg the next question as to whether or not the red/white painting most gantry structures in the early days used was also of a similar composition to provide the same service. Might have started out as red and white lead paint, the idea being to stand out to aircraft. Well, from what I've seen of the salt haze down there, some daze it's so thick that everything more than a few miles away turns the same greyscale and blends together. Besides, I'm pretty sure lead paint got banned decades ago; seems like even nitrocelluose aircraft paint won't stand up to that and heavy UV for more than a decade. So, I dunno what they'd be using now but it seems like you neglect that stuff for too many years and it all starts to corrode dangerously, hot-dipped zinc galvanizing or not... Maybe they're using some sort of thick coat polyurethane or suchlike? There are conversion coatings that are supposed to bond to corrosion and neutralize it. Don't get me started on the buzzard droppings. Nasty stuff. We need a local who actually works onsite; too bad Kim Keller's moved on. I saw the 'milkstool' up close back in the 70's, but all I remember it was a thickish grey paint. The gantry structures are definitely not painted the same as regular broadcast towers. They are pretty picky about the color and the stripes. Anything over 200' tall is supposed to be registered, lighted with beacons/strobes, and painted in seven equal bands of Aviation Orange / Aviation White (starting and ending in Orange). It's definitely not the "rust" color that you see in the old Apollo pad shots. Aviation Orange is quite striking when it's fresh... and they are picky about how faded it can get before it needs to be repainted. Since this is a government project, within restricted airspace, I suspect that they didn't have to comply with the same rules that everyone else does. I suspect they picked the right paint for the job. It would need to be durable, fireproof, corrosion resistant due to the marine environment, and relatively low maintenance. Probably had lead in it, at the time. The yellow paint inside the Saturn stages (oddly enough, I've noticed that myself) was probably picked for corrosion resistance, no flame spread, and relatively low mass. They may not have been fussy about that last one, though. And no cost was too high... just make it perfect and make it fast. My guess is one of the earlier named zinc chromates or something similar. -- Bob the Tomato |
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On Topic: Choice of paint used inside S-I stage
"OM" wrote in message
... On Mon, 28 Apr 2008 22:20:52 -0500, Damon Hill wrote: Yellow chromate primer to prevent corrosion of the aluminum? ...This makes sense, as the primer used on a lot of nautical items is the same type. It does beg the next question as to whether or not the red/white painting most gantry structures in the early days used was also of a similar composition to provide the same service. No; that would have been protected by 'red lead' first, then painted. |
#14
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On Topic: Choice of paint used inside S-I stage
On Apr 29, 4:24*am, "Alan Erskine" wrote:
"OM" wrote in message ... On Mon, 28 Apr 2008 22:20:52 -0500, Damon Hill wrote: Yellow chromate primer to prevent corrosion of the aluminum? ...This makes sense, as the primer used on a lot of nautical items is the same type. It does beg the next question as to whether or not the red/white painting most gantry structures in the early days used was also of a similar composition to provide the same service. No; that would have been protected by 'red lead' first, then painted. The following is a guess . . . not even a SWAG . . . I wonder if weight of the resultant protective layer (lead paint vs zinc chromate) could be part of the answer. I have seen a lot of zinc chromate used on aircraft, but not other places where weight is not as much of a consideration. Take care . . . John |
#15
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On Topic: Choice of paint used inside S-I stage
OM wrote:
On Mon, 28 Apr 2008 22:20:52 -0500, Damon Hill wrote: Yellow chromate primer to prevent corrosion of the aluminum? ...This makes sense, as the primer used on a lot of nautical items is the same type. It does beg the next question as to whether or not the red/white painting most gantry structures in the early days used was also of a similar composition to provide the same service. Nautical items typically paint over the primer - I suspect the gantries did the same. For that matter, you don't really need corrosion inhibiting primer if you have a good coat of good paint. The trick is maintaining the paint, because once corrosion starts it is a stone cold bitch to stop. Which is the real reason for using a corrosion inhibitor - belt and suspenders. D. -- Touch-twice life. Eat. Drink. Laugh. http://derekl1963.livejournal.com/ -Resolved: To be more temperate in my postings. Oct 5th, 2004 JDL |
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