Metal Finishing Techniques


Finishing Steel

Use a mixture of equal parts of liquid wax and boiled linseed oil. The wax is any liquid wax that we can find in the grocery, hardware, or auto store. We used to use liquid floor wax, but that has become unavailable in recent years (no plastic finishes please), so we have gone to the water soluble car wax that you "mix with water to wash and shine your car in one easy application."

To apply, we heat the piece just short of color and brush on. Continue applying until the liquid ceases to boil on the surface of the metal. Then quench in water and rub with a cloth. (Do not try this at home because the smell is horrendous and takes months to go away!) The finish is very durable under weather and mechanical action. Hinges, latches, dinner bells, etc. that are outside last for years before rust appears at the mechanically abused points. (Unknown Source from ARTMETAL mailing list)

For Indoor Work

Mix 60% boiled linseed oil, 40% turpentine, a dash of Japan drier . All available at your local hardware store. Make sure you remove all loose scale with rotary wire brush. Apply the mixture liberally with a brush and then wipe the excess off with a clean cloth. Re-apply as needed.

The thinning of the linseed oil allows for it to get into all the cracks and crevices. For exterior work: sand blast the piece and apply a zinc base enamel primer. Then apply a top coat. Sherwin Williams Commercial division has a graphite black premix that looks pretty good. It isn't as good as applying graphite dust while the paint is tacky, but repair touch ups are hard to match.

Final note. If you are quenching your work while it is still hot, a hard rust layer forms and is very hard to remove with wire brushing. (Enrique Vega from ARTMETAL mailing list)

Hydrogen Peroxide Finish for Steel

(From a discussion on "theforge" e-mail list)

For nice pitting, sprinkle granulated salt, sodium chloride, on the hydrogen peroxide dampened surface. You can control the pitting by: how closely, how many and the size of the salt grains you apply.

I tried out the hydrogen peroxide method for the first time recently, and was astounded with what I got.

It was a clear, warm day, and most of the surfaces were vertically oriented. I found that applying the HO with a spray bottle worked best. I used a newly opened bottle (for maximum strength) and did not water down the solution at all. Here's the method I used:

This is such a cool, easy, non-toxic finishing process that I plan to do a number of more experiments, varying the surface treatment prior to the HO application, (sanded, chemically etched, grinder marks, etc) and varying the application of the HO (sponge, rag, brush, soaked sawdust, etc) to see what happens. (Heath -Fusionworkshttp://www.fusionworks.nu)

Tinted Finishes

Robb Gunter has been using potters non firing stains with beautiful results. You might contact him for more on this technique, in Tijeras ,NM. He has one of the best blacksmith school facilities in the country.

A pleasant flat finish is a mixture of bowling alley wax with the colored powders used to tint concrete. (Remember those green yard frogs). Preheat the piece with the torch, apply the mixture with a rag or brush, then lightly reheat to dry and seal. The green mixture looks especially good on leaves. A book containing many good patina formula, for both red-metals and iron, is: Methods For Modern Sculptors (ISBN 0-9603744-0-X). It is available from Lindsay Publications, Centaur Forge and American Foundrymen's Society for about $20.

Mark Schwenk- artist/blacksmith at Frog Valley Forge

Clear Gloss Rustoleum-my favorite, shows all the details and works great in or out for years. Great silver black finish over mostly descaled work. Very artsy if you ask me. Reasonably chip resistant, quick drying, polyurethane is better against chipping but takes forever to dry.

Traditional Finishes

Nearly any wax or oil, or a combination thereof, will work as a metal finish. Make sure you remove all loose scale with rotary wire brush or similar tool. Apply whatever mixture you choose liberally with a brush and then wipe the excess off with a clean cloth. If you are quenching your work while it is still hot (red heat or better), a hard rust layer can form which is very hard to remove with wire brushing. Some common oil/wax mixes include:

Melted paraffin, boiled linseed oil, beeswax, and mineral oil

To make most wax/oil or solvent mixes USE A DOUBLE BOILER and heat the wax until it melts. Then add the solvent/oil. ****DO NOT DO THIS OVER ANY KIND OF FLAME**** An electric stove or heating element will work fine. Most solvents, like turpentine, smell pretty strong, so prepare only in a well ventilated area. Take the melted wax off the stove to mix in the solvent/oil. Pour it into some kind of a container with a lid and let it cool.

To apply most wax/oil finishes, warm up the piece of metal (pleasantly warm), and rub mix all over it. Then continue heating it until the wax starts smoking. At this point the wax is caramelizing on the surface, which hardens it a lot. You need to get it warm enough to caramelize all the loose wax (or you could buff it off later), and not so warm that the caramelized wax burns off entirely. Somewhere in between those temperatures the wax goes from light brown through dark brown to a nice shiny black. It takes a bit of practice (and patience) to apply this finish to an irregularly shaped piece and get a uniform appearance. You may hear this described as "applying the finish at black heat."

To heat small ironwork for finishing, try opening up a gas forge and holding the metal in the exhaust. Brushes for applying wax/oil/solvent mixes can be made from twine or hemp rope, tied into a shape like a shaving brush, with the ends trimmed and unwound. Cheap "natural" bristle brushes can be found at most Builder Square/Menards/Home Depot type stores. The brushes must be of a natural vegetable fiber. Synthetics will just melt onto the metal and "Goo it up."

George Dixon detailed his finishing method as follows:

Either hand sand or wire brush clean the metal surface. Mix 60 - 40 linseed oil (boiled) to turpentine. Brush this mixture on, remove the drips that slowly form. When this has dried, apply a good coat of varnish, organic rather than synthetic. This is more due to the plant base of the first mixture than anything else. When this has dried, apply several coats of a good caranuba base paste wax. Apply with a soft brush to get into uneven or layered surfaces. When the wax dries to a matte finish, buff the piece with a soft shoe brush to raise the luster of the wax. The use of brushes instead of cloth reduces lint and the bristles get into places a rag won't. This finish approach was used by the Samuel Yellin shop early in this century and work coated in this manner is still rust free, Again, this is an interior finish. Tell the customer to wax their iron as often as they wax their fine wood furniture, tell them which wax you used and how to do it. A card with "The Care Of..." that explains this is a nice thing to add with the bill!

A simple method of achieving a blue/black finish is to buff off the scale, heat until the metal turns about the color or colors desired and then spray with WD-40 and wipe when cold. William Hightower used this finish on bathroom towel bars, and "hasn't had a rust spot yet."

Appalachian Blacksmiths Association - Wax

Wax finishes leave a deep, lustrous glow to ironwork. They can be used for exterior and interior work. Generally, smiths blend equal parts of paste wax, linseed oil, and turpentine. A smaller volume of bees wax is then added. Japan Drier is available at art supply stores and it speeds drying time but is not necessary to harden the finish.

Some smiths prefer raw linseed oil to the boiled kind because it doesn't have drying chemicals in it. Some smiths mix bees wax with linseed oil and then use paste wax in the final buffing.

Beeswax can be used by itself. In fact, European smiths used it for centuries by simply melting the wax onto the workpiece while it was still warm. Unlike other waxes, bees wax is non-toxic and, therefore, can be used on cutlery and utensils.

Nearly all candles are made with paraffin. Do not confuse this wax with bees wax. Buy bees wax at a hardware store or from a beekeeper and use it.

For interior use, wax finishes hold up a long time and will only need an occasional buffing. Depending on humidity and precipitation, outdoor ironwork will need to be inspected at least annually. Rusty areas can be buffed clean with steel wool and then re-waxed.

For best results, ironwork should be warm (can hold in your hand) when applying the wax finish.

Beeswax Coating for Metalsmiths

http://www.youtube.com/watch?v=bcndMLZV7hs

Wax Finish, By Molly Schaffnit

Sootypaws Forge
Molly Schaffnit & George Monk
http://members.citynet.net/sootypaws/

Our finish recipe is derived from the one in Andrew's Edge of the Anvil:


Johnson's paste wax is used for the final waxing.

Since we apply our finish hot, we use raw linseed oil. Boiled linseed oil uses heavy metal driers. We prefer not to breathe those fumes. The piece is heated (just warm, not too hot) and the wax is applied with a mop (made of a piece of rag wrapped around a stick and held with wire) or the piece is just dipped in.

After cooling the piece is wiped off and set aside for two days or so. After the finish is fairly dry we apply a final waxing with Johnson's paste wax. The solvents in the paste wax dissolve any clumps of beeswax and the final finish is smooth and attractive after buffing.

This is a very durable finish for indoor use. It will stand for a year or more exposure in a protected area like a porch outdoors.

Appalachian Blacksmiths Association - Oil

Tung Oil and boiled Linseed Oil will dry and harden. Check the can and the label should indicate that driers have been added. They are toxic to the taste and should not be used on any ironwork that will be used with food or drink. Both are very durable. Tung oil is the better of the two if you will also be finishing wood. Tung oil allows the photoreactivity of the wood with sunlight. Linseed oil tends to darken wood over time.

For cutlery, utensils, and food wares, you will need to use vegetable or mineral oil. Keep in mind that vegetable oils will turn rancid. Thus, if you finish a knife and don't use it for a while, you will want to clean it well before using it. Mineral oil (a petroleum product) won't go rancid. Use only a very light coat of oil on your food wares.

A point about oily rags: they will spontaneously combust so dispose of them properly after finishing your work.

Wax for All Seasons, by Doug Merkel

A significant portion of my work deals with the repairs and reproduction of antique ironwork. Most of my customers want a natural finish that looks old, protects the metal and which can be touched up if needed without lots of work or fancy chemicals. To meet their needs I have modified a few formulas that have been around for sometime into one that works for me and my customers. For some of the larger jobs, I leave a small container of the wax for use by the customer. It wears well inside and does quite well outside, if applied correctly. I have a piece of ironwork with this finish that has been out in the elements for over a year without rusting.

The first three ingredients can be obtained at most any hardware store, such as Lowe's, Home Depot, etc. The Japan Dryer is used by artists to speed the drying time for their oil paints, so is available at many art supply stores. The beeswax can be obtained from a local beekeeper, beekeeper supply shops, or blacksmith supply companies.

Mixing The Ingredients

Put all the ingredients into a glass quart jar, put the lid on with the retaining ring very loose. A metal can may be used, but it needs a tightly fitting cover. Either set up a double boiler or set next to your forge to get the mixture to melt. Do not put directly on the heat source and watch out for open flames. Once the ingredients are melted, tighten the lid ring and shake like crazy until all the wax is dissolved and is a homogenous mix. As it cools, it will become a soft paste. Keep the lid on when not in use.

Metal Preparation

Remove all scale with a power wire brush or by hand. if you want a dark finish, remove the scale at a dull red and let the metal air cool until you can just handle it with your bare hands. For a brighter finish, use a power wire brush and remove all the scale while the metal is cold, then apply enough heat until you can just hold it in your hand.

Application

Apply the mixture with a brush, your fingers, or with a small rag. The heat will melt the mix and it will run into every nook and cranny. Let it cool and buff out with a rag. If you let the excess mix stay on the iron, it will eventually harden, but every place that has excess will show up as a bright spot. A second coat can be added to heighten the luster while the metal is cold. Just remember to buff off the excess with a cloth.




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