WELCOME to the anvilfire Guru's Den - V. 3.3

THIS is a forum for questions and answers about blacksmithing and general metalworking. Ask the Guru any reasonable question and he or one of his helpers will answer your question, find someone that can, OR research the question for you.

This is an archive of posts from May 1 - 7, 2011 on the Guru's Den
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Guru, I own a 25# Little Giant, and I am wondering if you would recommend the videos by Dave Manzer?
   Kelly - Sunday, 05/01/11 10:39:11 EDT

LG's. What you can afford. : I'm well known in the smithing field of endeavor, but no fortune as yet. I got a 25# Little Giant 35 years ago. I knew diddly about the mechanics of it. I could see that the Babbitt metal was cracking. I called some machinists to find out about Babbitt availability, and all I received was laughter. Finally, one guy said to try the windmill supply, and the windmill man on the phone said, "Yeah, we have it. Low speed or high speed?" I figured out how to pour the stuff, and I sooted the shaft with acetylene soot for an oil clearance. I found a 1½ horse motor which is really ½ horses too many, but it seems to do OK. I get about 3 or 4 licks a second.

If somebody wants to buy me a larger pneumatic hammer and install it for me, I'm open to that. Meanwhile......
   Frank Turley - Sunday, 05/01/11 11:06:12 EDT

The best powerhammer is the one running in your shop, paid for:)
As a guy with some real joint issues, that limit my ability tohand hammer any powerhammer is better than no power hammer.

My home buit started at 32#. Easy to build and work well up to say 5/8" square, and from there bigger much less acceptable. I upped the ante by going to 45# and a tire clutch and bingo, much btter hammer for what I do. But the slides on the ram were a little puny. I just recently upped the anto to a 70# ram, and much better wrp around slides. I can now rock and roll on the trowels I make, reducing the heats by about 5-6, and getter a better controlled finished forging that requires less grinding.
I have invested $ cost into the upgrades, now almost up to $250 total invested. My time I write off as machine shop fun:)
   ptree - Sunday, 05/01/11 11:47:04 EDT

Powerhammers : Jeff has it right; the best power hammer is the one you have running in your shop. I cobbled together a Kinyon-style pneumatic hammer for about $600 and a few days work. It's a 65# tup and it allows me to work stock up to 1-1/2" square. That;s pushing it, but it gets it done. On 1" and smaller it's a marvel and allows my ruined joints a well-deserved break.

I think one of the most overlooked benefits of a power hammer is that it allows you to save your hand hammering for where it really counts. Because the PH is doing the heavy lifting, you can spend more time on detailed hand work and really elevate the quality of your work and still actually make a profit. Even better, you can enjoy the hand work more since it is the high-end touches you're doing by hand, not the brute force section changes.
   - Rich - Sunday, 05/01/11 14:36:55 EDT

Best hammer is the one running. . . :
At one point I had four Little Giants. These were a 250, a 100 and two 50's. One of the 50's (mint) was used a bit when it was in our family shop where there was 3 Phase power. The other 50 had a noisy single phase motor on it and would have gotten used the most because IT was setup and running. They all went away when I thought I would never be in blacksmithing again. . . Every time I have parted with tools I have regretted it. .

In my current shop we had Paw-Paws NC green tire hammer. It got used a bit but the sloppy tube in tube guide system made it suitable only for long drawing operations and at 35 to 40 pounds running too slow it was not very good for that.

The hammers we are building that are just a little short of 100 pounds have forged more steel while testing with parts just tacked together than than Paw-Paw's tire hammer did in several years. The big difference is its over twice as heavy and has a good guide system.
   - guru - Sunday, 05/01/11 15:37:33 EDT

Hammer Dies and die space :
An interesting bit I learned from building this hammer is that while small dies (such as Big BLU's) are efficient and work fine for free hand forging they hamper the hammer's use for many production operations. I've been designing some multi-station fixed die tooling for producing some small tools that are well within the capacity of a 100 pound hammer but I keep running out of space. We have 3 x 5" upper and lower die holders and dies. The standard Big BLU free hand dies are 1.75" by 5". These work great and the narrow width cuts way down on the expensive tool steel. But they are way too small for what I want to do in production.

I can replace the bottom die and holder and get 6 to 7" of length. We added extra drilled and tapped holes in the anvil cap for this purpose. But the top die holder is just a hair smaller than the 3.5 x 5" ram in width. If I do not work to the corners I can squeeze another 3/4" out of the width. . . or use 2.38 by 5.75" dies. . . Still small for what I need to do. The option is to use two setups and thus two heats (a waste of fuel). OR use two machines (an even bigger initial cost). I was already planning on using a punch press for some simple operations.

Another option is to use tooling that does not attach to the ram and just strike it with plain dies. This introduces other issues but it probably balances out against making special top dies.

While all this trying to squeeze the last little bit of capacity out of the machine may seem petty it is not unusual. It is not unusual to see a lathe with the bed notched so that a part just a LITTLE bigger than the machine was designed for could be machined. I've seen a lathe with the bed extended just enough to get about half the tailstock onto the extension so a 20 foot piece could be machined on a 19 foot lathe. . . I've seen special short tools ground for milling machines to get that last little bit of height and we machined a part that weighed half as much as our Bridgeport with it resting on stock stands and supported by a crane. . ..

You always need a machine JUST a skosh bigger than the one you have. . .
   - guru - Sunday, 05/01/11 16:31:35 EDT

Power vs Hand :

For practical purposes the small power hammer replaces the relatively cheap and abundant labor that used to be available and is required for many blacksmithing operations. There are many operations shown in books on blacksmithing that do not tell you "two men" or "three men" required. . .

The same goes for all our electric tools. A little 1/4 HP motor will out perform most humans and larger motors are the most common, thus replacing several strong men. Hole drilling, grinding, polishing. . . all are power intensive OR tedious jobs.

Little machines are just as valuable in a shop as large ones. Many machines that can do tasks in a few minutes that would take all day by hand have motors less than 1 HP.
   - guru - Sunday, 05/01/11 16:45:24 EDT

Just a little bigger or faster : The guru is right, you always seem to have a need just a little bigger or faster than the machine you have.
At the valve/boiler and ice machine shops we had a huge variety and size range, yet often missed by a fraction. You can cheat on one offs, and if careful not hurt the machine or yourself. I have however seen many high precision machines destroyed by using too big a tool or running too fast or...
In our valve and fitting machine shop, where we produced something on the order of 500,000# to 600,000# of shavings a month, in a very muture, very competive market, every machine was run at least at 140% of rated capacity and speeds and feeds. We got away with that by buying the very best machines in its class, the very heaviest frame, and running the very best lubricants money could buy. We had oilers that faithfully maintained the oiling schedules and tooling was sharped in our own tool and die shops. When the older generation, all engineering to management group were replaced by biz school types the first thing to go was the non-productive oilers. The operators could oil their own machines. Then the cost of oils was biz-cased and cheaper oils were found. Its just oil after all, right?

Do I need to tell the rest of the story?
   ptree - Sunday, 05/01/11 16:51:32 EDT

On-line scams are proliferating and the scammers don't waste time.

No more than a week after setting up our Tailgate Sales page both Josh and I were contacted by the same person claiming they wanted to purchase relatively expensive items and have them shipped to the West Coast. The scammer agreed to our price with no question. The check was in the mail. . .

The catch is that the scammer wanted US to pay the shipping company and he would send the extra as part of the purchase check. At first I thought nothing of it but the whole deal had a smell to it. . . Then Josh was contacted by the same person with the same letter, same deal.

The way this scam will probably go (NOT) is that the check will arrive with instructions to wire the money to the trucking company and a bank account for the transfer will be included. So, you deposit the check that APPEARS to be a bank money order or some such official looking check, give it time, then wire the money.

But there is no trucking company and the check is a forgery that even if the bank SAYS it has cleared, may take a month or more to bounce. So you are out the shipping AND possibly worse, your credit is screwed up OR you are treated as passing a bad check yourself.

We found the name of the person attempting this fraud, and variations of it on-line linked to similar frauds. So there is a good chance that it is not even his real name.

This is just one of many frauds involving on-line sales.

IF the check arrives we will turn them over to the authorities along with the wire transfer account information. Then report what happens.
   - guru - Sunday, 05/01/11 19:03:03 EDT

Needing more : While we often find ourselves wishing we had just a bit bigger hammer or lathe or mill, etc, the corollary to that is that just as soon as we get that bigger tool we realize the damn shop is just *that* much too small to accommodate it comfortably. It never fails - that old "Economy of Scale" is an illusion. :-)
   - Rich - Sunday, 05/01/11 19:54:38 EDT

Rich, a collorary to Murphy's law is "Junk expands to fill the space allotted"
   ptree - Sunday, 05/01/11 20:27:11 EDT

Just ordered my AIA : Guru,
Thank you for the date info on the Arm and Hammer. I was in an Omish farriers shop in KY and was talking to the farrier about his anvil, he said he would be interested in when it was made and such. I knew I could get the info from you or one of your helpers here. Thank you.
I have been dragging my feet ordering AIA, but just put the order in in the anvilfire store.
Now the wait...

Again Thank you for all the help you have given me over the last year or so since the bug has bitten.

   Rustyanchor - Monday, 05/02/11 09:16:54 EDT

Mark, Its in today's mail. You should see it by Wednesday.
   - guru - Monday, 05/02/11 10:38:42 EDT

Power Hammer Foot Peddle Guarding : I wanted to say thank you to those who responded to my question. I believe that the foot treadle guarding is a good idea and will post pictures at a later date of what we come up with. The one comment regarding OSHA and the fact that injuries were the basis of the regulations rings home. While the hammers are a nice tool, they can also be unforgiving. Be safe.

Thanks again.
   Steven - Monday, 05/02/11 11:40:17 EDT

powerhammers : It is my opinion that someone starting out in blacksmithing learns how to work efficiently with hand hammers before they get a powerhammer. I earned my living at the anvil for several years before getting a powerhammer, and have done many things with it once I got it that some of the 'experts' in our local chapter said you can't do with a powerhammer. I also get the occasional offer (usualy from SCA types) who want to be my apprentice. I usualy refer them to my powerhammer and tell them if they can do exactly what I tell them, when I tell them, never get tired, never talk back, and don't cost me anything when not being used, I may consider it.
   JimG - Monday, 05/02/11 13:02:24 EDT

You forgot, never cost you time finding something for them to do. .

I've had both employees AND apprentices who would stand there shuffling their feet in dirt and debris while asking what to do next. . I stopped telling them to sweep up - I just reminded them that part of their job description was to keep the place clean and THUS, they should never, ever, ever, have to interrupt me to ask "what next?"
   - guru - Monday, 05/02/11 14:14:11 EDT

Ah Yes; one of my nicknames for a powerhammer is "The Smart Apprentice" as it does exactly what you tell it to do!

   Thomas P - Monday, 05/02/11 15:13:59 EDT

fly press : I,m in a quandry. I don't know whether to get a #4 or #5 fly press. The $250 price difference is something to think about, but I'm willing to pay it if the #5 is definetly worth it. I have a small, part time blacksmith business and don't do any real big stuff. I plan to go full time sometime in the next few years. Thanks in advance for any suggestions.
   - Steve Stransky - Monday, 05/02/11 17:09:11 EDT

Flypresses :
There is a #4, #5 and the Kaynes were selling an S5 which was a standard #5 with a heavier flywheel.

If you will note our discussion above about always needing just a LITTLE bigger machine (any type) than you have you may find you want the bigger machine. Currently the Kaynes are only stocking the #6 which is rated as the largest one-man C frame forging fly press.

Larger is better UNLESS you never use the machine. Like a lot of tools you have to learn to use it AND make tooling for it. Almost anything useful that you may want to do with one of these requires special tooling. That means at a minimum an arc welder and a grinder and realistically a saw and cutting torch as well. A (real) drill press is also good. I would turn a lot of tools on the lathe. See our iForge articles on press and fly press tooling.
   - guru - Monday, 05/02/11 19:05:14 EDT

I have a #2 fly press, which I've used a fair amount. But there things I'd like to use it for but don't because it's too small. I guess if you were doing really light work, tugging on a heavier flywheel might get tiring after a while. Nonetheless, unless I knew for sure I wouldn't be doing work too heavy for the #4, I'd go with the bigger press.
   Mike BR - Monday, 05/02/11 20:27:27 EDT

fly press : Buy the bigger one first. You probably won't regret it. If you buy the small one you almost certainly will.
   - Chris E - Tuesday, 05/03/11 02:54:35 EDT

air over hydraulic press : Hi Guru,I do a lot of closed die forging with spring swages, such as finials, balls etc. The largest stock I use is about one and a half inch round. I ususally forge these under a 130lb air hammer, but I'm looking for an alternative due to the noise etc. I was thinking a 50 ton air over hydraulic press might be suitable. Could you give me your opinion on whether air over hydarulic would work ok for this type of forging and if so, woud 50 ton be big enough for swaging this size stock? Thanks.

   mal - Tuesday, 05/03/11 03:11:51 EDT

Noise/Power :
Mal, I am not sure how to compare the 50T hydraulic to 130 lb. hammer. Hammers make fast repeated blows, hydraulics are slow thus need to do more per cycle. Using similar style dies to what you are using now, you are still going to need to have repeat cycles. Primarily to avoid flash and cold shuts. How quickly a hydraulic press can be cycled makes a big difference in capacity.

Forging references for required force needed to make a shape in a die impression are generally based on area (plan view) and few cycles. But how much detail you need and the change in cross section also come into play. Many variables to compare and it is often apples and oranges.

But 50T is quite a bit of power. A 40T machine will shear a 1-1/4" round steel bar cold and probably 2" hot.

As to noise reduction that is a completely different comparison. I've found that piston air compressors make more noise for a longer time than a power hammer alone. However, there is noise and there is noise. Some transmits a lot farther and is more bothersome than others. I have neighbors a considerable distance away (maybe 800 feet) that say they can hear our 100 pound power hammer when testing on soft wood. But that is perhaps because it is a DIFFERENT sound. In the growing season (now) we hear tractors and lawn mowers running almost every day in one direction or the other, kids on their 4 wheelers all weekend. . . If you are within a quarter mile of a construction site you can hear circular saws (perhaps one of the most grating sounds on Earth) and heavy equipment backup beepers all day. I used to live 3 miles and over several heavily forested hills from a rail road siding but I could hear the cars being coupled and shuffled around. . .

As to hydraulics, I suspect air over hydraulic is a quiet machine if you discount the air compressor OR have an electric screw compressor. I have a gasoline engine powered screw compressor that is much noisier than a piston electric due to the gasoline engine and will probably drown out the hammer its going to run. . . When I set it up I am going to put a good muffler on the exhaust and that should help.

On regular hydraulics I am told that they should not be noisy but all that I have been around SCREAMED. This is probably due to improperly designed valving and relief valves. But none-the-less, they were so noisy you could hear yourself think.

When changing from one type of machine to another you are often just trading problems. While a mechanical, electromechanical or utility hammer may be noisy they don't have the problems of leaking high pressure fluids, large quantities of inflammable fluids, the large number of seals to maintain. . . oil spills to clean up. . .

If you are adding a new machine and keeping the old then you are providing yourself more choices of how to do a job. You will also find that many forging operations benefit from multiple operations on different machines.

The norm in industry is a forging machine with a trimming machine (often a punch press) next to it. In closed die work there is a LOT of flash that is trimmed in a second operation. In open die work there rarely is flash but there can be a lot of operations. I'm currently looking at setting up a punch press next to the power hammer to perform steps that are suitable to the machine and will not fit on the other. The press will have two stations, the preliminary to forging offset and the name stamp (last step). In between these is several forging steps on one hammer. I am also looking at a product that is first forged, then drawn out on a McDonald Rolling Mill.

Production work (architectural work IS production work) requires a different way of thinking to be efficient. As noted above, machines are cheap compared to manpower.
   - guru - Tuesday, 05/03/11 11:37:28 EDT

I find that hydraulic presses suck the heat out of the work very quickly- meaning on small stuff, under 1" or so diameter work, the metal often cools before the press can finish doing its job.
In industry, they use very high speed hydraulic presses, which cost a lot more, and they preheat or constantly heat the dies.
Also, for things like a ball end, you need to rotate the workpiece while forging, which works fine on a hammer, but wont work in one heat on a hydraulic press.

Grant and others I know use powered fly presses, and they work better than hydraulic presses for many forging operations, as they hit faster, and do the work before the metal knows what happened, and has time to cool.

I do use my 30 ton hydraulic for some forging operations, but it doesnt usually gain me any speed- in fact, its usually a lot slower than a hammer- but since it only hits once, I use it for things where registration is essential, where I want one precise heavy hit. I often make hinged tooling for this, or two piece dies that might skate around a bit under the power hammer.
   - Ries - Tuesday, 05/03/11 12:46:17 EDT

Hydraulic forging presses : In industry, 40 ton is rather small. The smallest I have been around is a cute little 600T Erie 4 post. Most used a "prefill" valve to allow very fast traverse down to the work, and then lots of Hp to move the work. They also had seperate lift cylinders to very quickly lift the dies off the work.
A slow press does suck the heat from the work, and can lead to subsurface tears in the metal.
Water or a "less flammable" fluid is reccomended.
   ptree - Tuesday, 05/03/11 13:45:30 EDT

air over hydraulic press : Guru et al, thanks for the detailed advice.
   mal - Tuesday, 05/03/11 18:43:45 EDT

Scale (size) and Forging :
There is an interesting dichotomy in forging. The bigger the piece, the longer it stays hot and the easier it is to forge compared to a small piece that cools quickly and thus must must be forged much more quickly. While the large piece takes more force it allows more time to forge it.

Happily, the smaller the forging machine, the faster it can cycle as there is less mass to stop and reverse its motion. In mechanical hammers this energy is not wasted as most of it is stored in a spring and added to the next blow. This makes them very fast and efficient. In air hammers most of the return energy is wasted since less is effectively stored for the next blow. In hydraulic machines there is little inertia and all the return and most of the dead motion is loss. Small hydraulic machines also do not cycle faster intrinsically. They must be carefully designed to cycle as fast as possible which is the opposite of what hydraulics want to do. For any given HP you have high pressure at low flow (slow) or low pressure at high flow (fast).

So, given a proportional machine and HP a slow hydraulic press is good for large work and the fast air or mechanical hammer is better for small work. But the class of work (open die, closed die, coining, the amount of break down or change in cross section) is often more of a determining factor than size alone.
   - guru - Wednesday, 05/04/11 10:47:37 EDT

In hydraulics There is indeed a compromise, in that the input energy (Hp) can be used to move high volume or high pressure or any combo of the two that can be attained with the energy available.
Some "cheats" are to use accumulators, prefill valves on vertical machines and small diameter "traversing" cylinders that move the ram fast, but are not for actual work.
An accumulator is basically a "Battery" for fluid. Think of an air over water fire extinguisher. The flow from the extinguisher continues at almost the same rate until empty, because the stored air expands and maintains pressure. In hydraulics, the accumalators are mostly a bladder for nitrogen in a high pressure vessel. When the press in not moveing(usually most of the time) the pump output can go into the accumulator. The when high pressure high flow is needed, the accumulator can discharge and add to the pump flow.
I have seen 1000 Gallon accumulators in use on a 1300 ton 4 post forge press. BUT, nothing is free. The energy used per forging is the same as if the pump had the rated HP to make that combined flow. The infa structure may be cheaper.
That 1300ton ran a 7 piston Worthington pump driven by 70 hp. and the accumulator was a simple 1500 gallon high pressure vessel, charged with 1000 psi air, no bladder. working fluid was water. And when the rupture dics failed, and took the poorly excuted relief line off at a 2" pipe connection the escaping air and water made a mist that made escaping from the many acre shop difficult. I was 1000' away, in another building, with closed windows and put my earplugs in as fast as my hands could move, as I thought I might beeld to death through my ears from the noise!
   ptree - Wednesday, 05/04/11 14:08:28 EDT

Bobbing Compound : I've been making everything bladed with a finish of some sort, could anyone recommend an aggressive bobbing compound and good rouge for finishing steel in the white? Thanks.
   Thumper - Wednesday, 05/04/11 14:44:56 EDT

Bobbing? : Buffing?

First see Buffing Error FAQ

Then see Wheels, Grinding and Buffing

Terms are fairly important when dealing with buffing compounds. The second link above lists the four basic types, Rouge (very soft and fine), Tripoli (general purpose compound), Emery (black in variety of grits).

Unless you are looking for a really brilliant finish, and I DO mean brilliant you want to avoid Rouge and Tripoli when buffing steel. Emery is needed to cut hardened steel and alloy steels but doe not do well on stainless. Emery compounds come in various numbered grits from some manufacturers and in color coded grits from others.

Using the various compounds you can "cut" which is removing heavy tooling and grinding marks or "color" which is creating a bright finish.

Wheel coarseness and speed also come into play. Buffing wheels come in various materials and hardness. The soft cotton buff is "loose sewn" with about a 3/4" to 1" gap in the spiral sewing. A hard cotton buff is sewn with 1/4" or so between the spirals. Sisal and hemp rope buffs are used for very heavy cutting. If you want aggressive cutting then go with a sewn rope buff and black emery at a high speed.

Wheel speed in unit surface distance per minute (SFPM in English units) also determines how fast they cut. A fresh new 8" or 10" wheel will be aggressive at a given speed but when it wears down and inch or so (about 10%) you will notice a change in efficiency and when worn 20% it becomes very noticeable. I save wheel worn small to but on a higher speed machine AND for getting into tight places.

There is a fairly good article on buffing and SFPM in the (now older) Machinery's Handbooks such ad my 18th Edition. I'm not sure if the article is still in the current version.
   - guru - Wednesday, 05/04/11 18:58:01 EDT

Guru, sorry about the confusion, "bobbing compound" is a jewelery term for fast cutting, here's an example I found on Google.
And thanks for the tip on emery compound, never heard of it.
   Thumper - Thursday, 05/05/11 12:23:29 EDT

I also forgot to mention rubber wheels. These are rubber of various hardness impregnated with abrasive compound. Jewelers use them a lot. I'm not sure what they are called and only seen them in use. I think they are closer to a soft grinding wheel than a buff.

Your "bobbing" compound is called buffing compound everywhere I have seen it industrially. McMaster-Carr lists the yellow (as in your example) for both cutting and coloring. It is probably an aluminum oxide grit in wax but they do not say.

McMaster-Carr sells Silicon carbide powder from 16 to 1000 grit for hard materials but it is fairly pricey. They also sell a generic (IE undefined) "Lapping and Polishing" powder in hard and soft metal grades in grits from 40 to 320. AND they have aluminum oxide from 16 to 1200 grit. All these powders could be mixed with wax and made into a buffing compound. I'm not sure what kind of wax is used but it seems to be bee's wax for stickiness blended with a little of something else for hardness. But it could be the abrasive providing the hardness.

   - guru - Thursday, 05/05/11 13:36:33 EDT

There are two auctions going on this month with a bunch of blacksmithing tools. See May on our Calendar of Events. The Parlett Farmlife Museum auction in Maryland is a fantastic collection of old tools and machinery. Wish I had seen it as a museum.
   - guru - Thursday, 05/05/11 15:10:52 EDT

Rubber wheels with an abrasive---called cratex wheels around here after a major manufacturer of them.

Black compound on a sisel buff sure can easily erase any lines you laboriously ground into your blade!

   Thomas P - Thursday, 05/05/11 16:55:53 EDT

CRATEX. . I need to remember that. I recognized it as soon as I saw it. . .

Aggressive buffing is generally a bad idea if crisp lines and flat surfaces are important to you. Aggressive buffing is what you see on very cheap imported blades that go directly from forging to buffing. This results in shiny waves and dips, no bevels, overly rounded edges.

To get fast crisp results requires belt sanding and grinding with the proper platens and skill. A good bladesmith can go from the grinder straight to buffing but if they are picky they will hand work many of the surfaces with a stone or fine sand paper on a flat surface. Then all the buffing does is remove the finest sandpaper grit scratches.

Or there is the slow hand method in many steps. But either method avoids aggressive buffs. It all depends on the results you want. There are times where you want that wet or melted and rounded look. Then going directly from the forming process to aggressive buffing works.
   - guru - Thursday, 05/05/11 17:19:06 EDT

Parlett Farmlife Museum : Get there early on Friday, and you can still see the whole thing. I suspect that the auction and accompanying locust (including me, at least on Friday) will move through the buildings and the bidding will follow as we proceed.

It's a wonderful collection; and it's a shame it has to be broken up; but the family tried very hard to find state or private sponsorship, and over the last few years nobody has the resources to support venture's such as this. To give you a measure of the volume of the collection, 60,000 sq. ft. is about equal to one of my NPS museum storage facilities!

It’s sunny and cool on the banks of the lower Potomac; I’m still recovering, but making good progress- I can now walk a mile in about 18 minutes, and take a 40 minute walk without being out of too much breath.
   Bruce Blackistone (Atli) - Thursday, 05/05/11 19:02:43 EDT

CRATEX : Another name is BrightBoy.
Similar products.
I think now owned by Cratex.
   - Tom H - Thursday, 05/05/11 22:56:20 EDT

Brass Patina : I'm sure this has been touched upon in the past, but recently I have been doing a lot of brazing (old keys and brass plates). I have a small variety of etchants and acids, what works best to darken the brass to replicate age or patina?
   - Nippulini - Friday, 05/06/11 09:49:21 EDT

Aging Brass : Nip, It takes relatively strong chemicals to produce an aged looking patina on brass. One reason these alloys are popular is that they do not corrode easily. The faster you want to age a part the stronger the chemicals. Often the same acids that are used to clean metal are used to age them. The difference is the length of time in the bath, thus the amount of etch and how the part is handled afterward. If the etchant is allowed to dry in air you get further oxidation and the dissolved metal compounds stick to the part. However, you still need to be sure to neutralize any strong chemicals.

Acids tend to remove oxides and not produce color unless something else is dissolved in them.

Acids are generally neutralized with a weak alkali such as baking soda and strong alkalies are neutralized with a weak acid, followed by a weak alkali. Both are followed by a fresh water rinse.

Iron dissolved in an acid will discolor copper alloys. This is why there are warnings on products like Sparex (sodium bisulfate) not to use the same bath on different metals.

Note that Sparex (sodium bisulfate) is a dry powder that forms a partially killed sulfuric acid bath when dissolved in water. The dry form and the relatively weak solution are good reasons for its popularity. Heating the solution (like all acids) makes it work faster and be more aggressive.

Copper Nitrate (available from farm suppliers) used to kill algae in ponds is an easily available colorant. The part is dipped in a solution of the chemical, removed and let dry overnight, then dipped for a few seconds and allowed to dry again. . with each dip the colors darken and change. 5 to 10 days required.

Copper Sulphate also works.

Machinery's Handbook has a variety of copper coloring recipes with really nasty compounds of lead and other heavy metals. . . A recommended book is The Colouring, Bronzing and Patination of Metals by Richard Huges and Michael Rowe. Try Artisan Ideas for references on the subject as well.

Normally you want to start with a descaled clean surface (using Sparex as directed). This may want to be etched (soaked longer than recommended) or sand blasted to provide a flat textured surface with lots of surface area. Then start with your selected patination dip.

You can also purchase preformulated patination dips and coatings from folks like Birchwood Casey and art/sculpture suppliers. These usually work well and fast, and also have many of the hard to get compounds in them that you would otherwise have to purchase in bulk.

A popular tale is that artists would piss on a sculpture daily and let it age. . . probably works.

The last time I needed some brass parts colored in a hurry I only got a mild discoloration from copper sulfate, water and a bit of battery acid "borrowed" from a car battery. I precleaned with soap and water, then some vinegar. Like many jobs the being in a hurry (the customer wanted the parts TOMORROW) defeated the process and did not allow for experimentation.
   - guru - Friday, 05/06/11 10:59:29 EDT

More Coloring /Colouring Finishing :
To achieve a uniform final finish by chemical methods requires a uniform mechanical finish. The chemical finish will be no better than the mechanical.

We used to have a lot of aluminum parts anodized and some steel parts blued. Both processes were done by others. However, we put in a LOT of prep work by carefully cleaning and mechanically finishing the parts prior to sending them off.

All these parts were sanded with fine sandpaper, generally using a machine of some sort to achieve uniform results. Turned parts were sanded on a lathe. Flat parts were often finished using an orbital sander. The orbital sander made little round swirls about 1/8" in diameter. This is a nice non-directional finish that becomes less noticeable when etched. Some parts had one surface finished in the lathe then others with the sander. Holes were hand finished or a piece of sand paper in a wooden dowel was used with an electric drill. All this finishing often doubled the labor in parts. This is why vibratory finishers are so popular today.

The parts were generally cleaned with a strong solvent like lacquer thinner to remove any fingerprints then carefully packed in soft packing paper for shipment.
   - guru - Friday, 05/06/11 11:15:41 EDT

Coloring brass : Nip:

To darken brass, plain old liver of sulfur works fine. Also, Sculpt Nouveau sells a variety of patina products for all metals. They carry brass black made by Birchwood Casey which works quickly and very predictably. I use a lot of it in my shop.
   - Rich - Friday, 05/06/11 11:52:41 EDT

Anodizing : Having both worked ina large aluminum extrusion and anodizing factory in the previous century, I can offer the following,
The parts were always cleaned by dipping in boiling caustic soda followed bya flowing water rinse. A short dip in the caustic removed the fabrication lubricants mostly sheep tallow in solvent then, dirt grease and fingerprints.
If the part was a "frost" we left it in longer to gain a deep etch.

Many parts went through special built machines that textured surfaces, like sanding, scotchbrite wheels a distresser etc. These then hit the caustic, the rinse and then into the anodize then hot rinse then color then cold rinse to seal. Most were organic dyes.
I was just kid then, in pre-OSHA days. I was mostly the rack load/unload in that dept.

Later I did prototype anodizing in the lab for the Modelmaker at WABCO. Also used "Presto Black" from Birchwood Casey for steel parts.
   ptree - Friday, 05/06/11 16:02:15 EDT

sword/knife making : hey yall if you know of any master bladesmiths willing to take an apprentice PLEASE OH PLEASE TELL ME
thanks joe
   yellow - Friday, 05/06/11 18:19:32 EDT

Here, allow me:

   Bajajoaquin - Friday, 05/06/11 18:32:02 EDT

Patina : Guru,
You said something in the above post that confirmed what someone told me. They made rustic furniture, birdhouses etc. and used piss to age and give a rustic look to copper. They said they would rub the pieces down each day until they got the color/patina the way they wanted it.
   Mike T. - Saturday, 05/07/11 02:04:42 EDT

Coloring brass - book : There are a number of formulas in "Metal Techniques for Craftsmen" by Oppi Untracht.
   Frank Turley - Saturday, 05/07/11 08:23:07 EDT

Patination : The most authoritative compendium on patination I've read is "The Colouring, Bronzing and Patination of Metals" by Hughes and Rowe. Not cheap by any means but well worth it if you're serious about patinas.
   - Rich - Saturday, 05/07/11 11:17:04 EDT

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