Introduction: Annealing Metals (Copper and Brass) With a Hotplate to Make Rainbow and Different Colors Effects for Art.

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About: I am a part-time hobbyists biotechnologist with a photonics background. I also have a YouTube channel too. I work full time now.


A while back, I made an Instructible that i was annealing metals with propane, etc. It was interesting, but this is a good project. Instead of using propane, use a hotplate. I find that if not handled properly, propane can be "extremely dangerous."


Here is a new instructible on heating up metals (copper cups, copper sheets, copper only materials) with a hotplate instead of propane. We don’t want to use propane for several reasons: 1) it can explode. 2) It is potentially dangerous when misused. 3) Risk of carbon monoxide poisoning in unventilated areas. 4) If the tank tips, it can burn your house down, and insurance will not cover that.

Then we can use brass and other things like Bronze, but alloys of Copper tend not to work very well, unlike pure copper metal sheets and mugs.

You need copper sheets and protective gloves that can tolerate 500+ degrees C to prevent serious burns from the hot metal. You need a wooden table with clamps and support stands.

Also, i recommend you never operate equipment like a hotplate and metals when you are tired. Always be fully awake when doing this. (Safety). We need fast reflexes to make sure nothing bad happens!

I have tested brass (Copper and Zinc alloy) at those temperatures; they are interesting indeed, but the solder of the Mug I had was dripping on the hotplate (which is a lead-tin alloy). Remember that these alloys usually survive up to 900 degrees C without releasing zinc fumes. So keeping the alloy at 350-400 degrees C (Medium heat) is strongly recommended.

Do remember that heating things to 550-600 degrees C will release some fumes, so a well-ventilated area is needed. PPE like protective gloves and eye protection should be worn at all times.

Depending on the quality of metal, the annealing may take 10 minutes at 376 to 600 degrees C. Tongs could be used, but I recommend doing it with protective gloves (that can tolerate high temperature over tongs, since tongs are difficult to work with (that's what I find.).

The brass, if cleaned properly or is very clean to begin with, can produce yellow to orange color patterns.

You also need an IR digital thermometer, which is quite useful for determining the temperature. Mine can go up to 1500 degrees C, and its minimum temperature is -50 degrees C, but it was quite expensive.

Fumes that may be toxic in high amounts or irritating to your lungs may be produced when heating this high. I recommend a good ventilation system. Sometimes metals may have unknown materials that, when heated to 350-500+ degrees C, may produce noxious fumes. Beware of this.

Supplies

We need a good table. A wooden table is preferred, but a plastic table with wood placed over could work too.

We also need bricks (Large 7 inches by 7 inches Min) to support the hotplate.

The hotplate must go to 500-600 degrees C this is required to anneal the metals (heat the metals up to 600 degrees C).

  1. A hotplate that can handle up to 600 °C. Prefer 400 W to 500 W.
  2. Bricks
  3. A good table
  4. Tongs and protective gloves.
  5. Copper sheets from amazon.....https://www.amazon.ca/dp/B0B9MV7JD5?ref=ppx_yo2ov_dt_b_fed_asin_title
  6. Copper cups from etsy or e-bay.
  7. Brass sheets from etsy. https://www.amazon.ca/uxcell-Brass-Sheet-Metal-1000mm/dp/B08ZJBSL5Z/ref=dp_prsubs_d_sccl_3/147-9369965-2628638?pd_rd_w=EBgdo&content-id=amzn1.sym.59a596fc-cbca-4430-9c69-6051a14d4053&pf_rd_p=59a596fc-cbca-4430-9c69-6051a14d4053&pf_rd_r=KCZZH794GCERXKX95GN0&pd_rd_wg=JcpUo&pd_rd_r=5a911dfd-7704-475b-ad0f-99a917332125&pd_rd_i=B08ZJBSL5Z&th=1
  8. Fire extinguisher for metals is strongly recommended.
  9. Clamps and rods to prevent the metal from rolling off your hotplate ((Very important)).
  10. Fans to ventilate the area See beginning of the instructible for more info.
  11. IR thermometer (-50 degrees C to 600 degrees C) Check Amazon for that.
  12. Clean copper (the shinier the metal, the better off it will be when annealed).
  13. Aluminum foil and a basin.


Chemicals:

  1. 5-10% Acetic acid
  2. Optional (Silver cleaning wipes with NO thiourea!) -https://www.amazon.ca/Weiman-Silver-Tarnish-Remover-Cleaner/dp/B00G7TLDL8/ref=sr_1_6?crid=2E9UD4176JC56&dib=eyJ2IjoiMSJ9.1s0DXRKrMqIMn1fetwrvnSVcIMwoeL5pBEJmeYROmaD45yuQiZ2lNTp5VnZ_WUdVd2YhnWEmvpfO2tuzIHpxRjbOfevlFKMVRBseDbGJYWm37QHedk7IHyXtYBrTKIIxZFufA0QPbwKpHj_k2Cfx1R7RoybWFSu-hEaq5PiA1Ej1b5IuMMuzscLfJTkpGgsTMotDVEomsH1YDjvEZoUWSfN4LxT7KzB2eGpIh6YMGwxD68cH9DGH5ZduIiVMR6dEr3Hv4WSAy_5OeuNyZ2Oi8SZOkCPOx8-NDrXy001JAxo.J3_1bNd7wl3jBQ3j1EOVDJTVDIJUzkHk5MMStXNyoXc&dib_tag=se&keywords=silver%2Bcleaning%2Bsolution&qid=1759552716&sprefix=silver%2Bcleaning%2Bsolu%2Caps%2C114&sr=8-6&th=1
  3. Sodium chloride. Potassium chloride salt may work too. Please see step 2.
  4. Water distilled.

Step 1: Heating Up the Copper Sheets and Copper Mugs to a High Temperature-600 Degrees C.

Heat the hotplate on 3 to 4 bricks slowly to the max setting 5. A good hotplate should reach 500-600 degrees in 5 to 10 minutes. A hotplate requires constant supervision since it is dangerous to be left on without anyone around! Again, the table should have bricks placed on top to prevent the table from burning when you place the hotplate on the table. (Safety.)

  1. Using tongs or protective gloves (that can handle 600 degrees C) place the foil a few centimeters from the hotplate and allow it to anneal for a bit. The sheet, depending on the angle, will turn red, then pretty rainbow colors. Each technique produces different results. Protective gloves are much preferred over tongs (found out the hard way.).
  2. With the cups or mugs, you need clamps and support stands directly on the hotplate. You need the clamp to be 7 to 8 cm so u can place the metal directly on the hotplate. Using protective gloves (never do this without them) move the mugs, cups, etc around and heat the cups. Beware of fumes that may be generated; use a fan to blow the fumes away from you and open the doors to get the fumes to disperse. Proper ventilation is key here.
  3. A lot of the metal is trial and error. Thin foil at 0.001 cm thick (it can be ripped) is not practical, but the thicker foil can be heated for 1 to 1.5 minutes at 350-400 degrees C with your gloves put gloves on and place the foil a few centimeters on the hotplate. ((Center of the hotplate is the hottest). See supplies and Intro for more details.

Step 2: Work and Sucess With Brass (Alloy).

  1. Brass is a unique alloy, but bronze will work just as well. We heat up pots, etc, up to 300 to 500 degrees C. We move the pots with gloves that can handle 600 deg C.

Beware that some pots or antiques may actually leak lead-tin solder at 500-600 degrees C try to keep the heat of the hotplate around 350-400 degrees C for brass and for a limited exposure.

Some of these pots are very heavy, so you need clamps with bricks to make sure the (Hot metal doesn't roll off the hotplate onto you, causing injury and possibly burns to your skin.) Limit the pot weight to a few pounds. If it is too heavy, it may be awkward to work with. This is important. (Very Important).


2 . Cleaning old Pots with 10% acetic acid. Making a Salt bath with Acetic acid and aluminum sheets.

We can spray the pots with mild 5-10% vinegar to clean them in a basin with an aluminum sheet and sodium chloride. This produces a battery, which etches the brass and wipes it off with paper towels. If they are very dirty.... If they are too dirty, this may not be that easy.

I recommend a spray of 10% vinegar since it is easier to work with.

Sodium chloride + acetic acid << >> Sodium Acetate hydrochloric acid.

Potassium chloride + acetic acid << >> Potassium acetate + Hydrochloric acid.

NaCl(aq) + CH3COOH(aq) << >>> NaCH3COO (aq) + HCl(aq) Equilibrium.

KCl (aq) + CH3COOH(aq) <<< >>> KCH3COO (aq) + HCl(aq).

Keep the contact time with the salt low to prevent corrosion. This can be used to shine up the pieces. We need 5 grams of NaCl and 10% acetic acid in a plastic tray capable of holding 500 ml of salt and aluminum foil. I only keep it in for {{5 minutes}} to wipe down the material. The water should be distilled water to prevent contamination by other ions like iron, calcium, etc.

Fumes of acetic acid can be irritating since they slowly evaporate off. Use PPE (gloves, etc, to protect yourself and goggles). Work in a very well-ventilated area.

Step 3: Framing the Metal Sheets (Copper).

We need to find an appropriate foil of copper that will be 0.01 cm thick, 5-6 cm in length, and 4 cm in width. Then we place the copper foil from Amazon into the frame. The plastic or glass frames will work the best. This is the tricky part (Getting the frame and the copper foil that has been annealed to fit in.


Here are some frames I recommend for the display. https://www.amazon.ca/dp/B0C8RQJPC4?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1


https://www.amazon.ca/dp/B0CB5X591D?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 Golden frames (Painted over wood on Amazon.)

Step 4: Some Failed Results With Copper.

Here I tried to put the copper tea kettle (antique) with sodium chloride 5 g, with 10% acetic acid, with 500 ml of water (in a beaker). This is an old antique, so if I do some damage, it doesn't matter to me.


This creates a weak battery that can etch the copper if it is old, but corrosion and watermarks may result.

So be prudent when working with this type of battery. Even tho it is mainly 10% acetic acid, this is a strong acid, especially when mixed with sodium or potassium chloride, since some hydrochloric acid is produced.

This method failed since it was not clean (Shiny enough for the metal to oxidize.)

We use cloth to let the acid and salts dry and try to anneal the copper but this will NOT work well. I recommend a wipe (Silver wipe to clean copper, brass, aluminum with PPE) afterwards. These rags clean the metal with less toxic material than the thiourea material found in other creams, if you want to polish it (the metal very well). Let the cleaned material sit for 12 hrs.

Keep in mind that the aluminum will etch and corrode after 12 hrs of use. New sheets for this battery design are needed. Fresh cleaned salt water (Potassium chloride or Sodium chloride and 10% acetic acid.).

Step 5: Conclusions.

This is a better method than using propane ( see Intro for this, and there is no risk of an explosion like propane. You can get badly burned if you are careless, tho. Please be careful and do this ONLY in a well-ventilated area.

Always do this Only when you are awake and focused and have good reflexes in case of any accidents.

Thanks for viewing this Instructables.

SHOE0007.