Steps for a red-toned salt/fire patina

Prep The Copper

cut the copper - cut two sheets. It helps with alignment if the second sheet (backing sheet) is a little larger than the front sheet
sand both sheets on one side only - orbital sander, 50 grit. This will hide the scratches that copper inevitably gets.
draw the design on the sanded side of the top piece of copper

Melt on the Bronze

melt on the bronze with the flux-covered brazing rod and the oxy-acetylene torch. Use a #4 or #5 tip and keep it at approximately a 30 degree angle with the copper. Higher than that, and you risk blowing a hole in the copper.
Keep the torch moving so you don't overheat one area and melt a hole in the copper. The torch and the brazing rod are usually moving in different directions. The torch is preheating where the rod will be going to next. I prefer to let the red-hot metal melt the bronze, rather than the torch, but sometimes I need a little extra heat from the torch to keep the bronze in the melting mode.
You should use goggles but I don't. With green goggles, I can't see the red glow of the hot copper, and I can't see if I'm doing it right
Wear a mask or have good ventilation. The flux fumes are not good for the lungs.
Near the edges, you will have to pull the torch away from the copper - often 5 or 6 inches. Otherwise, you will melt the copper.
Make small circles with the brazing rod to get that stacked dimes look.
Don't put on the bronze too thick and textured - that impedes assembly later

Do the Salt/Fire Patina

Flatten the copper somewhat with your hands
Set the copper up on some concrete blocks, so you will be able to get the torch under it.
Sprinkle on the copper a 5:1 blend of salt:baking soda
Have a salt shaker with salt in it, ready to go.
Put the rosebud tip on the torch and turn up the oxygen and acetylene. Light the torch and turn it up. It will be quite loud.
Use your heaviest, thickest welding gloves, the ones that go half-way up your arms and look like oven mitts.
The torch goes under the copper - You heat the copper from below until it gets red hot - then sprinkle a little salt on it from your salt shaker and move on.
Concentrate carefully and keep the torch moving. It is very easy to make big holes in the copper with this technique. Don't try to talk to anyone while you are doing this.
When you have finished, turn off the torch and take the copper over to the washing area. You have about 5 minutes to get it rinsed off. Rinse quickly with a soft stream ( too much water at this point can wash off some of the delicate new patina). Don't try and get all the salt and baking soda off just yet.
Dry completely on a flat surface - this is important to bond the patina to the metal. Don't dry with the copper anything but flat - you will get unpleasant streaks and runs.
Don't dry in the sun - the patina appears to be light (or is it the heat?) sensitive in the sun. Sun drying makes the patina go brown.
Then flatten the copper by hand and soak under wet towels for 12-24 hours
Rinse off any white flux remaining - this might require some light prying with a small wood stick - go over the brass carefully and get it all up. Rinse off any remaining salt and baking soda - if you don't they will go green.
Set the patinated copper on a wood surface and smooth out with gentle hammer taps - use rubber hammers - the oak slapper works well here
Put the patinated copper on a sheet of pink foam and scrub the back with Dawn detergent and a scratchy pad. (Don't use a grinder with a wire wheel. That work hardens the metal.) Rinse and dry. To speed dry, soak a cloth with acetone and wipe the back.
On the backs of both copper sheets, the patinated and the sanded plain, spray Rustoleum 2081 Automobile primer - its gray and oil based - let it cure for at least two days. The sanding on the one sheet and the scratching on the other will help the primer to adhere better.
prepare the marine plywood for the metal - cut it a little larger than the largest copper sheet - coat both sides with water-based Varathane or similar. If you do this, you won't have to put two coats of glue on the wood (the first soaks in too fast to be useful). Let this dry 6-12 hours
Do the gluing in a room that is at least 60 degrees - see my gluing tips page. Use Dap's Weldwood solvent-based contact cement, available at most hardware stores. Apply the contact cement to the primed copper surface and the varathaned wood surface - put it on thick, don't over brush. Let it dry, then reapply. Wait about 30 minutes, then get out your heat gun (Wagner?) and carefully dry the areas that are still wet. Test with your fingers - you want it tacky, but not gooey. If it comes off on your fingers, keep going with the heat gun. Don't over-dry the already dry parts. Dry both sides at the same time - you want them to have an equivalent level of glue that is slightly tacky. The heat gun helps make the glue warm and helps the whole process.
When the glue is ready, put the glue-covered marine plywood on a sturdy table. Use silicone paper to help with the line up of the copper to the wood. I buy Seal silicone paper from United Manufacturers. You will want 2-4 pieces. First cover the whole glued marine plywood area with silicone paper. Then gently lay the glue-covered copper on the silicone paper. Check the line up and the determine where the corners are. Then, lift up a portion of the copper, remove a piece of the silicone paper, then press the copper down, exactly lined up. Then gently lift the unglued portion of the copper, remove more of the silicone paper, press the copper down. Repeat, until all the glued-copper is touching glue-covered wood.
Put the glued copper-wood assembly on a sturdy table. Starting with the center, hammer out to the corners along all the diagonals and center lines (think British flag pattern). Then work out from the center along the middle lines. Many times you are actually shrinking the metal (it stretched while you were heating it). So you want to trap it, then carefully work out the domed areas. This is where the glue helps. Use rubber deadblow hammers and the oak slapper. I often hold two hammers at once, one in each hand with the hands touching - this saves wear and tear on my elbows and forearms and covers a larger area. Then I will shift to a smaller hammer to work out any domed areas and air pockets.
Now, repeat the process with the backing piece of copper
Set the glued copper-wood-copper laminate aside for a few days, preferably in a 68 degree or warmer room. Air out the gluing room
Spray the front with one coating of Krylon clear coat. This is to protect the patina from the abrasive used by the water jet cutter. Dry 12 hours.
Draw the design on the copper - use a fine tip sharpie. Be very precise.
Take the copper to your water jet cutter
Explain to him exactly what you want - be very specific about the outside edges. Cover any visible wood with blue tape - be sure to tell him that you don't want to see any blue tape on the outside of the final cut pieces
Pick up the waterjet cut pieces. Wash them off as soon as you get home. Let them dry thoroughly on an open metal rack for two days.
Nest all the pieces upside-down on foam, then remove the raised ridge from the backs of the edges - use a coarse 3M pad on a grinder.
Now carefully glue up all the unglued metal-wood portions, and any broken plywood laminates - I use polyurethane glue like Gorilla glue. be careful to keep the glue off of the surface - use silicone paper between the surface and the clamps. Clamp with Irwin type clamps - springs clamps aren't strong enough. Use pieces of luaun to even out the clamping pressure and to cover larger areas.
Clean up all the oozed-out dried-up glue with a rasp or a razor
fill all holes with wood filler - I use Elmer's
Prime the edges of the laminate. You could use my special polyurethane blend. Clean the fronts as you go.
Let dry two days.
nest all the pieces again on a piece of metal. Spray with Klean Strip stripper - after 15 minutes, rinse off with a high-pressure water spray. Rinse the sides too. Let the pieces dry for 8-12 hours. Clean off any remaining Incralac with acetone.
Sand lightly, then edge black with a satin black acrylic-latex outdoor paint. I add a tsp of 403 silica to mine.
Re-clean the fronts with acetone. Be careful to not leave any swirl marks. Use a very clean cloth and keep rotating it to another clean area.
Use package sealing tape to remove any lint from the cleaned surface
Blast off any remaining dust with an Air Can
Spray on a coat of Incralac. Let it dry 4-8 hours
Spray on another coat of Incralac. Let it dry 8-12 hours
Check the surface. If any areas are tacky, force dry them with the Wagner Heat Gun.
Wax the surface with a 50-50 blend of Renaissance Wax and Bowling Alley wax. Apply the wax with a circular pattern - not back and forth.
flip the pieces and clean the backs with a 3M pad on a grinder. Electric grinders are best - the weight helps.
Wax the backs with the wax blend.
The pieces are ready and you're ready for assembly!

Following are my previous notes - I will combine them as time allows

How to Create a ‘Salt-Fire’ Patina on Copper 12-27-05

This patina typically has a lot of red in it, plus oranges, brown, blacks and copper colors

Typically, this is done near the garage door opening with the garage door open for ventilation and to facilitate taking the copper outside to wash

Also, we want the salt to be as near the door as possible. Salt tends to absorb water from the air and it is hard on the concrete when it gets ground into it

To begin, flatten the copper you will be flaming with your hands – no need to use a hammer

Set up a table a little below waist level and put 4-10 bricks on it, standing on end

place the copper on the bricks – make sure there is room enough below the copper to use the rosebud tip

You will be using the Harris torch with the Rosebud tip.

Both the acetylene and oxygen regulators should be set in the 5-10 range – adjust as needed.

Turn on the acetylene only, light the torch and, as quickly as possible, get the oxygen dialed in to help minimize soot in the workplace

You don’t want an excess of oxygen – this tends to blow a hole in the copper. An excess of oxygen is a flame with no inner orange cone. You want an inner orange cone about 1-2 inches long.

Remember – if the copper is taking too long to heat, put the torch closer to the copper and/or increase the flow at the regulators

Start the patina with the corners because these are easiest to heat.

Sprinkle salt on the copper and, heating the copper from below, get the copper red hot and melt the salt – a black crust will have formed, which will turn red as it cools

Then move to the next area, being careful not to go over the area you just did

If you do go back over a previously torched/salt-melted area, the red patina will peel off and leave an orange and black patina – sometimes this is desirable for variation

If you sprinkle the salt on before the torching, you will have a smooth red patina

If you sprinkle the salt on during the flaming, you will have a mottled pattern with lighter specks where the salt fell on the red-hot metal

If you don’t put any salt on at all, the copper will go black

Slowly and methodically torch the whole piece. Don’t jump around - It is easiest to heat the metal next to where its already been heated

If there is brass melted on the copper, avoid melting the brass any further.

Also – avoid heating the areas near the brass that are golden and champagne and copper colored – these are beautiful just as they are – don’t lost more than 50% of these colors

Be careful not to overheat the copper past the red point – a quarter second too long in one spot and you have a big hole that has to be dealt with

Note that the bricks will get in your way and you will have to move them one by one as you go around the piece

When the copper has all been torched, remove it from the table, take it outside and wash it off

Wash both the front and the back

Be very careful not to wash the front for more than 60 seconds. The red patina is fragile at this point and can be washed off

Set the patinated copper in a warm area away from the sun and let it dry for 6-12 hours in a flat position

Sweep up the salt on the table and the concrete

Removing the white flux

After the copper patina has dried for about 6 hours, flatten the patinated copper with your hands and lay it on the concrete floor

Lay towels on top of the patina and then pour water on the towels – let sit for 12 hours or overnight

The next morning, remove the towels and rinse off the front of the copper

Go over the patina carefully looking for any flux that didn’t get removed – white or glassy-looking - remove it by rubbing with a sharpened piece of wood (not metal), then rinse the surface again.

Here's another guide I wrote earlier

Melted Salt Patina on Copper 5-28-06

This is a mottled, organic-looking mixture of bright reds, dark reds, oranges, browns, blacks and salmons (near a flux bronzed line). You do not want to just get reds

Your goal is to get the copper just hot enough to melt the salt – that’s it. This is a dull reddish color. If you go to a bright reddish color, that’s too hot! You won’t get a nice variegated patina.

If you go back over an area on which you’ve already melted the salt, you will get nice speckled oranges

If you go near an area and get it hot but don’t melt the salt, you will get nice blacks and browns

You want this variation in color – not all one solid color

Start with a clean sheet of copper

Prop up the copper on 4 or more bricks – don’t use concrete blocks – they absorb too much heat

Sprinkle a very light layer of salt over everything

Alternates are a 5:1 salt:baking soda sprinkle. The baking soda will help the patina stick to the metal better and will also give darker reds to purpley reds

Use the rosebud tip with the oxy-acetylene torch – have a slight cone on the flame. If you have too much oxygen, the flame will be flat

You are heating the copper from the underside – watch where the flame is turning the copper red – once it gets red, sprinkle salt on it then move on

Salt is the preferred sprinkle – put some rice in the shaker to help prevent it from clogging up the holes. Also, store all salt and salt shakers in plastic zip-locked bags

If you overheat the copper, you will blow a hole in it. This takes about ¼ of a second. Don’t let yourself get distracted!

You will be sprinkling salt almost all the time you are heating the copper. A light steady sprinkle on dull red-hot copper is what you want

In general, you want to do ‘U’ or ‘ZigZag’ patterns with the torch. You want to stay an ¾-1 inch away from all bronze lines. You want to save a lot of the salmon color near the bronze lines.

Be very careful with edges and corners – they heat up much, much faster than inside areas. It is very easy to melt an edge or blow a hole in a corner

If you’ve done a bad patina, there are a couple of ways to fix it.

Cover half the patina with a wet towel and try to redo the technique. If that works, redo the process with the wet towel over the other half

If that doesn’t work, you will have to strip off the patina (this usually takes two tries) using the Behr Concrete Cleaner/Etcher, wire-brush the surface, cover the bronze with either – Cool Blue, Handi Jig or a Baking Soda/Clay mixture – then redo the patina

Handi Jig mixed with baking soda is my favorite though the clay idea sounds good – get some clay from Chandra.

After torching

Let the patina sit and air cool for two minutes – set a timer

If you have Handi Jig on the bronzing you will want to save it. Drop the copper on its edge on a concrete surface. Scoop up the Handi Jig and put it back in its jar with some added water.

Lay the copper face down on a non-abrasive surface and hose off the back – 30 seconds of water should clean it adequately. Use a strong jet to get off as much loose material as possible.

Then flip it over on its front and lightly mist it for several minutes, until all the salt has run off. The red patina can be very delicate at this point, so don’t go blasting it off with high pressure water

Hold it by a corner for one minute to let the water drain off, then set it down flat on the floor in front of a fan to dry

Do not let it dry lying in the sun or leaning against the wall

The red patina is often very fragile when wet and can run down the surface in streaks. It needs to dry to really lock on to the copper.

Note on Baking Soda – this should help neutralize the chloride ion and prevent green patina forming where the salt hasn’t been fully washed off

If you’ve blown some holes in the copper, normally those will have to be repaired by brazing on a small patch from the backside

After the patinated copper has dried, you will need to lay the metal flat on the concrete and cover the surface with wet towels. The towels should be on for at least 12 hours. The purpose is to remove all water-soluble flux, baking soda, salt, etc.

The next day, remove the towels and carefully clean off the surface

Inspect the bronze for any remaining white flecks – if some remain, remove these with a dull wooden tool

If any green patina or staining is evident, rub that off with towel and water, then rinse again

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