Jump to content

Cleaning Bench Marks


patw

Recommended Posts

Many bench marks are not simply covered with trash but are seriously corroded (oxidized?).

I carry a stiff brush and a can of kitchen cleanser with a jug of water to clean them off before taking the picture but the corrosion is impervious to the cleanser. Two questions:

1. Does the NGS object to our efforts to clean a bench mark?

2. Does anyone know of a preferred method to remove the corrosion?

Hint: The picture will generally be improved if you wet the bench mark first.

. . . . patrick

Link to post

Why clean them? As long as you can read it, what do they need to be cleaned for? They are just going to corrode again. In fact, the corrosion layer, once established, probably helps protect the rest of marker. Chemicals in the kitchen cleaner might do more harm than good over the long term. Several I've found that were placed in the 30s and early 50s are still readable without any cleaning.

 

As for wetting the marker for a better picture, I agree. I usually spit on the center to make the station designation easy to read. Considering I'm usually wiping off mud or bird crap, a little spit isn't so objectionable. Think about that when you look at the pictures I post.

 

rdw

Link to post

Although practical, it is a little gross. All of the markers I've found have been legible and fairly clean, but then again they have all been on the sides of buildings. I'm interested to hear what some of the other opinions on this are.

 

- Dekaner of Team KKF2A

Link to post

Hello everyone, Im here to promote, and to thank you for, your interest in Land Surveying.

 

The oldest brass cap markers were set nearly 100 years ago. They are now in varying states of disrepair. Please avoid cleaning them in any way that may damage the marker. If you find one in especially poor condition please make an affort to inform either the responsible agency, such as your state department of transportation, for example, depending on the markings on the cap. Alternatively, you may wish to notify your local Land Surveyor and ask him to forward the info for you.

 

For further information about Land Surveying, please feel free to visit us at rpls.com and ask any questions you may have.

Link to post

quote:
Originally posted by survey tech:

Hello everyone, Im here to promote, and to thank you for, your interest in Land Surveying.

 

The oldest brass cap markers were set nearly 100 years ago. They are now in varying states of disrepair. Please avoid cleaning them in any way that may damage the marker. If you find one in especially poor condition please make an affort to inform either the responsible agency, such as your state department of transportation, for example, depending on the markings on the cap. Alternatively, you may wish to notify your local Land Surveyor and ask him to forward the info for you.

 

For further information about Land Surveying, please feel free to visit us at rpls.com and ask any questions you may have.


 

Thanks for your informative posts on the subject of surveying and benchmarking. It's good to hear from somebody with experience in the field. I'm sure we'll all benefit from your observations and advice.

 

Bluespreacher

Link to post

Good evening. I have not taken up this area of the hobby yet, so I may be speaking of something that doesn't matter. If so, please disregard this message.

 

I have 20 years of experience with Brasso. It does work great. BUT.... it contains ammonia, and that will weaken brass. You need to decide for yourself if this matters. For instance, I am a competitive shooter. I DO NOT clean my rifle or pistol cartridges with brasso. Should I even need to polish my military medals, I could use brasso. Most likely, I would just dump them in the brass tumbler for my reloads. Just a friendly warning.

 

Mike. KD9KC

El Paso, TX.

Link to post

quote:
Originally posted by KD9KC:

I have 20 years of experience with Brasso. It does work great. BUT.... it contains ammonia, and that will weaken brass.


 

Well then Brasso should be avoided! Anything that would weaken the disks should not be used.

 

My opinion is that they shouldn't be cleaned/polished down to shiny metal at all. The greenish patna works to protect the disk from further corrosion and should be left intact. If necessary, a wet rag with some mild detergent will get most accumulated crud off. Just my $.02

 

I'm not lost!

I just don't know where I am.

Link to post

quote:
Originally posted by Couch_Potato:

Well then Brasso should be avoided! Anything that would weaken the disks should not be used.

 

My opinion is that they shouldn't be cleaned/polished down to shiny metal at all. The greenish patna works to protect the disk from further corrosion and should be left intact. If necessary, a wet rag with some mild detergent will get most accumulated crud off. Just my $.02

 

I'm not lost!

I just don't know where I am.


 

I still like the spit. It doesn't take much and you don't have to carry something extra.

 

rdw

Link to post

I'm trying something new. I clean the top with a plain old paper towel- nothing else- then daub on some white shoe polish. Then before it can dry, wipe it off. This leaves the original patina alone and highlights the stamped text for photography. Here is on example at DX1228. It did not work real well on this one but has worked on another. I think the yellow construction marker would work too. I will try that soon.

 

nscaler

"Anyone not here, raise your hand!".

Link to post

I tried the yellow crayon trick. It looked lousy. See UWDawg's photos at SX1249.

 

"If a boy has enough intelligence, he ought to go into the ministry, except that if when he enters college he is given to carousing, drinking, and wenching, then in that case he should enter the law." - Harvard Student Review, 1796

Link to post

I was just reading all of this fuss about cleaning of the markers and I would think that you would'nt want to disturb/clean them in any way. You can try a digital image and then invert the colors(negitive) to show the hidden features.

 

If you can't get a picture that really shows the markings and or wording, you should do as Indiana Jones did and use Charcoal and a piece of Paper to "rub" an image/impression that can be photographed. icon_cool.gif

 

Sofa, King, We, Todd, Did

Link to post

I was just reading all of this fuss about cleaning of the markers and I would think that you would'nt want to disturb/clean them in any way. You can try a digital image and then invert the colors(negitive) to show the hidden features.

 

If you can't get a picture that really shows the markings and or wording, you should do as Indiana Jones did and use Charcoal and a piece of Paper to "rub" an image/impression that can be photographed. icon_cool.gif

 

Sofa, King, We, Todd, Did

Link to post

After looking at these things for many years,the oxidation becomes a protective coating.I believe the USGS markers are made from bronze.Can anyone confirm this? I'll be adding to the collection here when I get my other 'puter back up and running again.

Link to post

They are made of brass, an alloy typically containing copper and zinc. Using bronze, a more valuable substance, would have been too expensive and also would have made the markers likely targets for theft. Its important that everyone understand that these markers lose all their value as soon as they are disturbed in any way. Even being removed and put back, they become worthless, which is why they are typically taken away when they are knocked over, or even merely bumped, during construction. In fact, moving a marker can cause serious engineering problems, raising the cost of development in the community. While it is not illegal to possess a destroyed marker, anyone seeking to sell such markers may be subject to questioning regarding how they got it. I have a few myself, which I have found destroyed in the course of my work, but I would never try to sell them.

Link to post

I am coming into this a little late but I would offer this viewpoint.

 

With experience from military school and jewelry making, I would suggest the following. There seems as though there are two types of deterioration or dirt that are on the benchmarks. The oxidation(green) and maybe tarnish and patina. It might not be bad to remove the green oxidation but DO NOT remove the darkening or patina of the metal. DO NOTbring the benchmark to a high polish. That will expose fresh metal to the environment that will cause that to oxidize and tarnish and if the next guy does the same thing, you might notice, you will actually be assisting in the deterioration of the metal. Use of metal polishes that may contain some chemicals that can actually cause reactions with the metal can also actually cause a deterioration of the metal. Also some of these polishes actually have fine abrasives in them that will actually remove some metal, making the marker thinner, and expose fresh metal to further deterioration. You should be able to remove any dirt or debris with simple soap and water and a light stroke with a VERY SOFT toothbrush. Lightly brush to remove dirt etc. DO NOT brush hard enough or enough to bring a sheen. That is exposing the metal to further aging.

 

You might consider using the crayon method or MAYBE shoe polish might help some. I would check the contents of the shoe polish though as it can have some solvents in it that might harm the metal. Whether a crayon, which might actually be best, or shoe polish carry a couple different colors. A light color and a Dark color. If you encounter a brass or bronze marker that has turned a deap brown color you migth want to use, say, white wax to make the writing stand out from the natural color of the marker. If on the other hand the marker is a greyish or light color than you might want black or brown to make the writing stand out. A crayon or shoe polish contains wax which may actually help to preserve the finish of the benchmark. That is assuming it doesn't contain an abrasive, solvent or other chemical that can harm or react with the metal. As for the yellow crayon, that may be suggested considering black and white photography or using a filter at the same time. I seem to recall from photography in school that you can make clouds stand out in B/W photos by using a yellow filter. Yellow can change the darkness level of the releif enough to make it stand out on B/W film. With color photography, on the other hand, it might not be as effective. Personally, I think I would use the crayons. Using water and a soft cloth, I would lightly clean the mark to remove grit and debris. Then wipe on the wax (crayon) and wipe it off. THE KEY HERE IS LIGHTLY. That way you will leave the wax in the relief of the marker or around the embossed letters and make them stand out a little. The wax, as I said, MIGHT actually help preserve the marker a little.

 

One other tip that comes to me from my photograpy experience is, You might want to have a flashlight or a reflector of sorts with you. A white piece of cardboard or some foil taped to a piece of board etc. Shine or reflect light onto the marker from a low or flat angle from the side. If light is extreme, from above or straight on, it gets into the markings as well as on the face of the marker illuminating everything evenly, reducing or filling shadows, and minimizing detail. That will cause your image to flatten. Shadows are what give you detail. By going from the side, the light will either stay, somewhat, out of the engravings causing shadows inside them or cast shadows off of embossed or raised lettering and make them stand out in your pictures.

Link to post

Try welders chalk sticks. They stick to metal (temporarily). After applying the chalk, rub the marker and the letters will have a little chalk left in them with the rest of the marker being "clean". We used to do this to find serial numbers on oilfield equipment prior to servicing. Non-destructive, effective, and cheap!

 

icon_eek.gif Fat, drunk, and stupid is no way to go through life, son!

Link to post

Try welders chalk sticks. They stick to metal (temporarily). After applying the chalk, rub the marker and the letters will have a little chalk left in them with the rest of the marker being "clean". We used to do this to find serial numbers on oilfield equipment prior to servicing. Non-destructive, effective, and cheap!

 

icon_eek.gif Fat, drunk, and stupid is no way to go through life, son!

Link to post

I went out today and found my first benchmark. It wasn't difficult at all since it was only a couple blocks from home and the discription was enough for me to know exactly where it was and what I was looking for. I am sure some of my future hunts will be a little more challenging.

 

Anyways, I took the information in this thread into consideration and evaluated some of them in relation to what I found. First off, the marker that I found was about 4 feet above the ground and on the front of a monument. There was some green oxidation in the letters but surface was nice and dark and had a good patina. There was no need in having to enhance the engravings as they were adequately filled with the green which made most printing stand out. However, the stamping of the date and the ID number were not as easilly read. Might be due to the fact that they are not as deep or wide as the engraving and thus didn't have as much green in them. I also took the photography technique I provided into consideration and noticed that in the NGS guidelines they somewhat suggested the same thing. Do not attempt to potograph from straight on. You will get reflections or glare off the marker. Shoot from a slight side angle. That also helps to have shadows cast off and into leters relative to the camera angle. I shot from slightly asside the marker.

 

I did use a yellow crayon as is suggested by NGS. Contrary to another post here I found it to work pretty good. I also saw one other picture in the recent logs that used yellow crayon as well. I thought it looked OK except the finder didn't clean the excess off the surface. The only thing I can guess is that the problem might have been that the writer who thought it looked bad might have gone overboard with it. You don't need to go too far with it. Just go over the Stampings. You don't really need to go over the engraving as that is pretty much understood anyways. Also the engraving is more accurately imprinted and should deeper, heavier and easier to read anyways. Once you go over the stamping with the crayon use a piece of paper towel and wipe off the surface of the marker. Work the crayon into the stamps. You will notice that it does help the writing stand out a bit.

Link to post

I was up in central Maine and have found a few benchmarks. These are not the traditional metal disk type. These where set in the 1800s and are simply carved into rock. After 200 years in the rain, they are in remarkable shape. The original carving is present followed by each update.

 

The trouble is that they are covered in lichen and overgrown by foliage.

 

How best to clean these up so they will be around for somebody else to discover in 2200?

 

To start, I see no harm in a soft brush cleaning.

But how does one remove the stuborn lichen what will break down the rock over time?

 

Can anything be 'painted' over the rock to prevent its regrowth and perhaps to seal it from

acid rain....?

 

I will try to also approach people who restore old gravestones. The same methods should be appropriate for benchmarks.

 

Any knowledgable ideas?

 

Skye Sweeney

Link to post

For chemical treatments, unless you know all about the chemical makeup of the rock, trying anything might be dangerous to the rock.

 

Painting on or soaking in polymers like paint or epoxy could trap moisture, resulting in worsening the ordinary freeze-thaw degradation of rock.

 

Poisoning the lichen would probably help, but it would be temporary. Eventually the chemical would be gone and the lichen would be back.

Link to post

After a little research, I found several web pages that are devoted to cleaning and preserving gravestones. The jist was:

1) Never to use any kind of brush that is harder that the stone. Plastic scrub brush and tooth brush are best tools.

2) Use plain water for cleaning.

3) If needed a SMALL amount of household ammonia.

4) Consult a restoration expert for anything else.

 

I wonder what the fee would be to drag some expert to the top of some remote back woods mountain in Maine to clean the top of the mountain! :eek

Link to post

I think that the person who sugested doing the rubbing with paper and charcol had a wonderful idea. If you can't get a good picture then make a rubbing of it then photograph the rubbing. Just be carful when you do the rubbing so that you don't dislodge a fragile maker that is in a state of deteriation.

Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...