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 Post subject: How to discover what lies beneath?
PostPosted: Wed Jul 02, 2008 2:00 pm 

Joined: Sat Oct 02, 2004 5:48 pm
Posts: 380
Location: Hickory, NC
A 90-year old Southern Railway bridge was recently demolished in our little city of Hickory, NC, and the DOT engineer overseeing the bridge project (done for a road widening) was kind enough to give me the original cast signs from the bridge railings.

I had to call a wrecker service to send out a Rollback and we had to winch the 20-foot long signs up onto the truck and have them hauled off.

I suspect at one time, the entire sign had "Southern Railway" spelled out on it, perhaps with its famed herald in the middle. I don't know why I feel this way, as I have seen many SR-stenciled bridges and signs, but none quite like this.

Anyway, this current sign has at least one coat of white paint, one of silver, and god knows what else beneath it. The white and silver are just of my lifetime, I have no idea what was beneath this, and no old timers are left around here to tell me what it said either.

Can anyone suggest a method (other than elbow grease and lacquer thinner) that might reveal what lettering and scheme might be below these quick maintenance coats of paint? If someone can Xray a Da Vinci painting and see his original sketch, perhaps the same can be done on this massive RR sign? (I know, maybe not cost effectively, maybe not on metal).

But I had to ask.

Thanks

Matt Bumgarner


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 Post subject: Re: How to discover what lies beneath?
PostPosted: Wed Jul 02, 2008 2:10 pm 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 6464
Location: southeastern USA
Matt: ya gotta dig. Paint layer analysis is actually a fairly enjoyable part of many preservation projects. I'd get some sandpaper or a sharply pointed Xacto blade, pick an innocuous corner, and cone down through the strata so that each successive layer is visible as a band. You might be surprised to discover that the layers are different in different parts of the sign, which could indicate a multicolored livery or a spot repair, depending. Caveat is that colors of pigments tend to fade before recoating, or chemically change over time, so a more reliable idea as to real color choice results from moistening the revealed layers.

Have some fun with it - hope you find something interesting.

dave

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“God, the beautiful racket of it all: the sighing and hissing, the rattle and clack of the cars over the rails. These were the sounds that made America the greatest country on earth." Jonathan Evison


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 Post subject: Re: How to discover what lies beneath?
PostPosted: Wed Jul 02, 2008 6:28 pm 

Joined: Thu Aug 26, 2004 4:59 pm
Posts: 351
Location: western Maryland
You sound pretty serious, with the wrecker and rolloff trailer, in your desire to find out what the lower layers consist of. Get a small, portable sandblaster and a couple hundred pounds of walnut shell media. Walnut shells are fairly soft and go to dust pretty easy. That allows you, with extra care taken on the angle you point the nozzle, to remove a layer of paint at a time.

Anybody less serious can use the exacto knife method. : )


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 Post subject: Re: How to discover what lies beneath?
PostPosted: Wed Jul 02, 2008 6:56 pm 

Joined: Sun Aug 22, 2004 7:19 am
Posts: 6464
Location: southeastern USA
I'll have to try that - but I've never been able to control any blast media to the extent of limiting the affected area to less than a couple square inches. I've limited the area to maybe a half inch square with sandpaper, less than a quarter inch square with the knife method, leaving all the layers visible in the 'hole" at the same time when finished.

dave

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“God, the beautiful racket of it all: the sighing and hissing, the rattle and clack of the cars over the rails. These were the sounds that made America the greatest country on earth." Jonathan Evison


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 Post subject: Re: How to discover what lies beneath?
PostPosted: Thu Jul 03, 2008 12:25 am 

Joined: Thu Apr 14, 2005 9:34 pm
Posts: 2836
Location: Copenhagen, Denmark
Back in 1986, they were sandblasting a GG1 at Strasburg on the engine service track. As we passed by every half hour (inbound and outbound every hour) I was able to see it progress from Conrail, to Penn Central, to Pennsylvania colors.

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