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Tips about Soldering

Updated: Feb 20, 2022

Developing repeatable and safe work habits..

Terms: Understanding soldering terms and techniques.

Alloys and Melting points and of silver:

Fine silver: Pure silver is called fine silver and is 100% silver.-------------- Melting point 1,761 Fahrenheit

Sterling: Sterling silver is an alloy of 92.5% silver and 7.5% copper.------ Melting point 1,635 Fahrenheit

Alloy: An alloy is a mixture of metals to acquire specific properties.

Solder: Solderis an alloy fine silver, copper and zinc and tin to lower its melting point.

Alloys and Melting points and of solder:

Solder alloys:

Solder is an alloy of fine silver, copper, tin, and zinc. The percentage of each metal is different for each desired melting point.

Easy solder: silver 56% / copper 22% / zinc17% / tin 5% ------ Melting point 1,205 Fahrenheit

Medium solder: silver 70% / copper 20% / zinc 10% --------------- Melting point 1,360 Fahrenheit

Hard solder: silver 75% / copper 22% / zinc 3% ----------------- Melting point 1,450 Fahrenheit

Step 1: Be sure that the metal is thoroughly clean of all oil, dirt and oxidation. To make sure your parts are clean, wash your metal and solder with Dawn dish soap and hot water. Body oil from your fingerprints can interfere with solder flow, so don’t touch areas once they've been cleaned. Lightly sand the area. This is what I use to clean the area to be soldered. Tropical Shine, Cushion nail files #707301 Fine-400/600 color pink. Purchase them through Sally Beauty Supply, You can wash then to keep them clean.

Step 2: The pieces being soldered must fit together tightly. Solder can’t jump a gap and neither can heat. It's imperative that they touch or your solder won't flow across the junction.

Step 3: Apply the flux. My method is to use boric acid and denatured alcohol. I dip the pieces in the mixture then light the alcohol to burn it off leaving coat of powder boric acid on the surface. Then I heat the piece to melt the boric acid, creating a boric glass coat on everything. Place the solder at the junction of the pieces. Then I apply one or more coats of boric acid then heat to glaze it. This coat will help hold everything in place.

Step 4:

Slowly heat the metal evenly until the solder flows. Remember the solder will flow to the hottest piece, practice controlling your heat and watch closely what happens.

Step 5: Use the smallest torch tip or flame size that you can to do the job. That will give you more control and keep you from overheating your piece. This can help when working with delicate findings that you may be working with.

Tip: Flux is an oxygen barrier that stops the metal from oxidizing and makes it easier for solder to flow.

The flux I use 90% of the time is boric acid and denatured alcohol.

Most jewelers use Handy Flux paste, its borax and water. I use it about 10% of the time. The problem with it is the water. When you heat it, the water boils causing the pieces to move and it doesn’t prevent fire scale where the sterling is exposed. Most jewelers use a Fire-scale preventing product but using my method, it’s done with one product. The boric acid coat will stop Fire-scale. Fire-scale is the oxidation of the copper on the sterling alloy. The oxidation needs to be removed for subsequent soldering operations.

Boric-acid is soluble in alcohol and borax is soluble in water.

Boric-acid is removed by putting it into your pickle pot the same as when using borax flux paste.

Safety Note: Keep your boric acid and denatured alcohol in an airtight container made of glass or metal. Keep it away from flame when you’re working and have the cover handy to cover the container in case it ignites. Stay calm and deliberately cover the container to extinguish the flame.

I have my apprentices practice this so it doesn’t startle them and they will remain calm when it happens. You should do the same. You should be familiar with how to be safe.

Keep a fire extinguisher close by if you ever need it.

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