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darryl
11-04-2003, 02:59 AM
Ok, now that I have made the soldering copper, as it's called, for soldering sheet material, we have another problem. The sheet copper from the supplier has slight scratches from handling, and the bending process introduces more scratches. Does anyone know of a way to remove these slight blemishes from the copper, in some efficient manner? The copper, after fabbing, is to be coated with a protectant, to keep it's like-new shine, and prevent tarnishing. One solution I suggested is ordering it with a peel-off layer, but it isn't available that way, at least not from the current supplier. Another solution suggested was to order a 'flat' which is, if I recall correctly, 100 sheets. The idea here is that no one has touched the sheets, so they should be 'virgin'. We, of course, need to handle it, and there will be the inevitable scratches. What we need is a finishing method that doesn't drive the cost up, but does leave the original lustre of a virgin sheet. Ideas, anyone?

Evan
11-04-2003, 04:01 AM
I have a 4x8' sheet of 20 guage out in my garage. It has a mill finish that is not the same as what you would get if you polish it. I think you will find that if you try to polish out scratches you will have to polish the entire piece to make it match. I can't think of a way to approximate the mill finish. BTW, if you buy a "flat" unless the sheets are separated by paper they will have slip marks by the time it gets to you. When I worked on aircraft it was a requirement that the 2024 alclad sheet not have ANY scratches and a scratch was suffcient to cause rejection of the work. Alclad sheet is supplied with paper on both sides and often layout is done on the paper.

Another item that you likely already know is that you should handle the copper with cotton gloves to avoid tarnishing.

[This message has been edited by Evan (edited 11-04-2003).]

Forrest Addy
11-04-2003, 04:27 AM
Workers in decorative metal soon learn to protect the finish of their materials with almost hysterical care. Their metal supplies are always handled with clean cotton gloves, placed on clean newspaper covered carpet scraps, stored with paper separator sheets, handled in a clean work environment (no bench grinders or wire brushes around), and worked with polished or padded tools. Sheet cut in a foot shear is always slid in on a sheetsof cardboard when is then slid out before the cut.

As I said, almost hysterical care. This level of care in metalworking is a PITA in the beginning but as soon as you get practiced it becomes second nature.

Make your desires knows and a good non-ferrous metals supplier will ship your sheet copper properly crated and protected agaist all hazards. If any sheet arrives scratched he should replace it. This service comes at a premium which is why most small consumers pick their stuff up.

Cass
11-04-2003, 04:28 AM
One way might be to paint the copper and then strip the paint after the fabrication work is done. That used to work with steel sheet metal work to prevent rusting from finger prints. There are also some protective tapes that are used for protecting finished surfaces during handling but that approach would be expensive for large areas. 3M makes a spray on stripable protective coating that is an orange color. It is intended for protecting polished surfaces and it easily removed. It is can be poured on also. We usually put masking tape on top of it because there will always be one spot out in the middle of a surface that didn't come up. The masking tape picks it all up. If you can avoid the scratches, finger prints can be removed by using a so called "bright dip" as a last step which lightly or strongly etches the copper. Some kind of a sulfuric acid solution I think.

WJHartson
11-04-2003, 12:52 PM
There is an electro polishing process that has been used on aluminum and stainless. Guess it would work on copper. The item is placed in a bath and a current is run through it that removes the high spots on the material. The surface has very polished look. A friend of mine that has used the process said that it was a lot cheaper than trying to hand polish the aluminum and stainless pieces. I think the company that did this for him is in Mobile, Alabama.

Joe

darryl
11-04-2003, 01:46 PM
Thanks for the replies. It seems then the first course of action should be to get it supplied stacked with paper. I'll look into that. The spray on protective coating sounds good also. So does the slip sheet sandwich when shearing and bending. And, yes, I'll wear cotton gloves while handling it. I didn't during the prototype phase, but then the pieces were scratched anyway, and as it turns out, the prototype was scrapped. Thanks again for the ideas, you all have an excellent day!

Peter S
11-04-2003, 06:03 PM
Joe,
I have had a bit to do with electro polishing - in my experience it does not remove scratching. It does turn a flat 2B finish into a nice shiney one, though.

Evan
11-04-2003, 06:50 PM
Darryl,

You should make yourself a wooden rack (assuming you don't already have one) to hold usable part/whole sheets safely. For aircraft aluminum we had racks to store the sheet metal standing on edge individually. It's safer to store the sheets on edge as there is less chance of kinking thin sheet when handling. The rack had a slot for each piece about an inch wide with the edges facing the sheets covered with thin carpet. Rack was 8' deep by 4' high so it could hold full sheets. Make as wide as needed for the number of sheets to store but not more than about 3'. It takes two people to put a sheet in/out of the rack. Also, a good source of newsprint for placing between sheets or under a sheet on a table is your nearest newspaper printing press. They have roll ends they usually give away that still have 50' or 100' on them. When cutting on a shear you can avoid marks near the edge by cutting through drafting tape. It also works to use drafting tape on the nose of the shoes of a box and pan brake. Note I say drafting tape, not masking tape. Drafting tape comes off without residue.

wierdscience
11-04-2003, 10:49 PM
I once visited a coppersmith up in Tennesse,he had plastic tooling in all his brakes,benders etc.,also noiced all of his hand tools where chrome plated and polished.