As any silversmith knows, silver solder is the ideal material to use when joining sterling pieces by the traditional method of brazing. Sometimes I will receive an object which has been lead-soldered in the area in need of repair (or re-repair). Sometimes the joined area is not visually accessible, and I don't know if lead has been used.
In either case, I cannot use silver solder because the high temperature required will melt any lead in the joint and allow it to form its own alloy with the silver. Not pretty! And, using a low temperature tin/silver solder won't give me a sound joint or good silver color. For this reason, I had been exploring newer technologies for joining metals. I tested laser welders from a few manufacturers, but found that their compartments are too small for working on holloware. In addition, they are expensive to buy and notoriously expensive to repair, and the down-time for repairs can be substantial. I also tested the Mini Pulse III (an arc welder) from Aelectronic Bonding, which had too few welding power options and didn't allow me to get into tight spaces.
I tested a friend's Lampert PUK 2 pulse arc welder for a few months, and refined my technique to the point where I felt confident to purchase Lampert's PUK 3s Professional, which was developed to weld silver more successfully. I was so impressed that I soon purchased the PUK 3s Professional Plus which had a broader power range, additional impulse settings, and five programmable settings.
Since I use the PUK on a daily basis, it was only natural to upgrade again to Lampert's latest model: the PUK04, which has the following advances over the previous models I've owned. Features in bold were the most important to me:
Above: As with every PUK I've owned, this latest model also sits to the right of my main bench where I can pivot left to get access to my abrasive and burnishing tools. I set up ventilating behind the welding area to capture all metal fumes. Venting or using the optional smoke absorber is a necessity, as with all other forms of welding which produce metal fumes.
The 10 electrodes come pre-sharpened on both ends. I wait until I have used all 10 electrodes (20 tips) before sharpening them at the same time with the supplied mandrelled diamond disk. This saves time. I mount the disk in my Foredom handpiece and secure it to the bench over the dust collecting vent. The recommended tip angle is 15%. Electrode replacement in the PUK handpiece can be accomplished within five seconds.
Advice on welding larger objects
Whether it be pulse arc or laser, welding isn't meant to substitute for brazing large objects. Welding long seams (e.g., on coffeepots or candlesticks) is more time-consuming than simply using the welder to tack a seam in preparation for brazing.
If attaching parts to large bearing surfaces (e.g., a large finial to a coffeepot cover), it's best to tack the part in place, then use the capillary action of torch-brazing to fill the void. Always consider the time it will take to weld or braze and the subsequent clean-up.
Lampert pulse arc welder highlights
Uses the same alloy as the piece being created or repaired (no color
issues as with solder);
The basic cost for the PUK04 is $5,295. It includes:
PUK unit and microscope;
Optional accessories I added:
The articulating arm ($575) allows me to work on larger objects underneath the microscope. See it in use here.
The precision regulator ($135).
When I was using the PUK 2, I tried a couple of different (and less expensive) argon regulators that weren't nearly as accurate as the one from Lampert. Most argon regulators are made in China and have graduated indicators that are too close together and/or have poor adjustment sensitivity, and very poorly made (I returned two regulators before springing for the Lampert model). A regulator that doesn't give accurate readings can lead to poor welds and wasted gas. The PUK regulator is very well made and has more widely-spaced indicators to better indicate exactly how many liters per minute of gas is flowing. Though it's priced at $135, it's a wise investment in German quality.
Argon gas, which protects the weld from developing oxides, is the other expense for running the PUK. Without gas, the PUK won't run (and you would never produce a successful weld without it, regardless of your chosen welding apparatus). To reduce the cost of argon, I would advise leasing a 300-cubic-foot cylinder (5' tall x 10" diameter). I'm paying $86 per refill plus $50 for the yearly lease. Argon purity of at least 99.97% is recommended by Lampert. The industrial argon I'm using from my local Airgas company is 99.995% pure. I have been running the PUK on 1.5 liters of argon per minute regardless of the allow I'm working with.
Additional electrodes each set supplied with a diamond grinder and case ($45).
1. Pin module for welding ear studs
Definitely purchase a
Speedwire Welding Wire Dispenser (not a Lampert product)
Using this relatively new technology has broadened my scope of options when joining metals. I can mend a pinhole with a dollop of sterling, dress it down, and give it a quick polish without disturbing the patina. The end result: absolutely no indication the piece was repaired - the color is perfect! I can repair a bezel surrounding a piece of glass without removing it. Normally I would be forced to unmount the glass, possibly damaging it in the process. I even used the PUK to weld a steel wire to the end of a hardened steel pin that was buried in a candelabra stem. I heated the stem, melting the lead solder, and pulled the pin out. How slick is that?
When I say I use the PUK every day I'm working, I'm not exaggerating. It was the most prudent (and expensive) purchase I've ever made for my shop, but it's already paid for itself. Once you own this little gem, it will open a whole new world of possibilities. Oh, another plus: it's great fun to use!
Lampert PUK04: (excellent)
Lampert's Web site (Germany)
A&A Jewelry Tool
(Los Angeles, CA)
4/12/2013: Engraving Cleaner
There are times when using a glass brush can be messy and even get in the way of a good weld. Plus, the tiny fibers can get lodged in your skin and can be very difficult to find. Today I made this engraving cleaner which will free-up your flexshaft for other accessories. The screw can be loosened and rotated to expose new material.
As with soldering, welding also requires a clean surface. This is especially true with engraving, which can be very deep. When I see oxide build-up (not soot), I reach for the cleaner. The cleaning will also aid in void-free welds.
4/5/2013: Filling Engraving
This rare Jensen piece shows its chased lettering filled with sterling (left). The image on the right shows the finished job. I used 2ms, thick mode, 50% power. The material on this tankard allowed me to use a more powerful pulse. Remember to always start with a less powerful setting so not to blast through the object.
4/2/2013: Filling Engraving
Below is the bottom of a stelring creamer part of a five-piece teaset that had to have the monograms filled in. The material was too thin to eradicate, and the customer wanted a replacement monogram engraved. See more of monogram filling here.
Top left: I removed all oxide in the engraving with Wright's Silver Polish and a horsehair brush (a typical flux brush). It's best to start with a clean surface. I used silver polish since it's less abrasive than a glass brush or 0000 steel wool.
Top right: the engraving being over-filled with sterling wire (I used these settings: 2ms, thick mode, 50% power).
Bottom left: the monogram totally filled.
Bottom right: no trace of the monogram after planishing, abrading, and polishing.
3/10/2013: Flattening filler wire
On my PUK bench sits a small anvil for flattening my .010" / .25mm filler wire which comes out of my Speedwire dispenser. There are times when I need a thin piece of sheet to fill a narrow split.
3/9/2013: Skimming (my term)
There are times when you'll want to build a heavier thickness on top of what you're welding. Below is a weighted candlestick with the pitch still inside. Previous welds on this piece had not yet been refined, as I simply wanted to get all holes filled first.
I'm using a much heavier .020" / .51mm wire on the edge of <.005 / .127mm sterling. This is a fairly advanced technique, for you'll want to position the electrode on the edge of the wire, pushing a small amount onto the area beneath with a light setting. I'm using the thick sterling setting, 1ms, and 35% power. This would never be enough power to melt the entire wire, but will melt a portion of it. This technique is also allowing for a much thicker base to weld to without blowing through the thinner material beneath. Using a heavier wire will cover the hole much quicker than using .005" / .127mm, and will give me a much thicker base to add heavier amounts of silver. Later burnishing will also result in a smoother surface. Another plus in using thicker material will be found in argon savings.
Below: The filled hole
2/21/2013: Smoothing deposited metal
I discovered this technique yesterday which allows me to free-up my flexible shaft for welding accessories. This $20 Dremel electric engraver, with its 9 power settings, hammers down, massaging the metal while giving a beautiful smooth finish for light filing and sanding. I removed the engraver point, polished the other end, and reinstalled it. The engraver is very loud, so I wear earmuffs. I feel the deposited metal is much less traumatized than when working with many rotary burnishers which "pull" the metal instead of compressing it like a rolling mill.
The area in front of the deposited sterling was finished with a #4 pillar file then 1200-grit wet/dry paper, ready for polishing.
I will start searching for a quieter electric engraver.
2/20/2013: Cast iron/sterling welding
Yesterday I made a hanger for my grinding wheels' truing device. This is an example of successfully welding sterling to cast iron. It's not a pretty connection (I wasn't concerned with aesthetics), though the weld is extremely strong even though there is very little contact between both materials. I used the sterling mode with the thick preset. Periodically removing any soot from the welding area will guarantee a homogeneous meld between weld layers.
2/7/2013: Stainless welding
I did some stainless welding today with no filler wire. The blade in a dinner knife snapped off its tang. I removed the tang from the sterling handle, welded its circumference, and made it ready for reinsertion. If I had silver-soldered the two pieces back together, there most certainly would have been some etching to the blade from the flux. Cleaning of the tang and welding took all of three minutes!
1/8/2013: White metal welding
Up to now I've been demonstrating how fantastic the PUK is at welding silver. You may remember the successful test I performed on pewter. Yesterday I was straightening, leveling, and polishing a white metal sailing trophy. One additional repair was required: reattaching the ship's wheel. White metal generally melts below 300 F (149 C). Since there was a large gap that required filling where the wheel meets the handle, I used some higher temperature lead-free pewter which melts at approximately 450 F (232 C). I used the sterling setting with a time of 1.5ms, thick mode, 35% power. The pewter performed beautifully, filling the gap and leaving a brighter color than a traditional tin/lead solder. (I do no plating, so the pewter color was a great substitute for a silverplated finish. Plus, this was a repair, not a restoration project.) The pewter also gave me a considerably stronger join. Gently bending the wheel back and forth proved the welded areas were successful.
11/20/2012: Void-free welding
Below is an image of a piece of .040" (1.02mm) sterling sheet that was built-up to a thickness of .105" (2.67mm) using .020" (0.51mm) sterling wire. Notice the lack of voids do to successful melding of weld deposits. I used a setting of 2.5ms / thick mode / 45% power, pulsing over and around the sides of the wire. I then dropped the settings to 1.5ms / thick mode / 45% power, and placed the electrode at a 45-degree angle where the partially melted wire meets the sheet. This allowed the wire to puddle, melding with the sheet and leaving no voids. I then cut a cross-section with a sawblade and finished the face with 2000-grit silicon carbide paper.
When building upon melted wire, make certain that there are no voids underneath, otherwise, the area (when cut on a profile like the piece below), will look like a sponge and will not have structural integrity.
I welded two pieces of .040" (1.02mm) sterling sheet together with .020" (0.51mm) sterling wire, allowing voids (the dark areas of the weld) to develop in the process. I then split the seam by bending, demonstrating what can happen to a joint when not totally filled. Insufficient power was used when the electrode was positioned on top of the welding wire. The result was that portions of the underside of the welding wire didn't fuse to the sheet.
10/22/2012: Using brass wire wheels
When using a typical 3/4" brass wire wheel in a flexible shaft to remove soot and oxide build-up, use very little pressure and a slow speed. Not doing so may leave brass residue on the piece you're welding and will lead to an unsuccessful weld. Welding doesn't like the presence of an addition metal which isn't part of the alloy you're welding.
10/21/2012: Tools I use with the PUK
Front row, left to right...
Back row, left to right...
PUK compactor (teeth removed, slightly flattened side), flexshaft mandrel with four sides (not pretty, but works well), 45-degree heart bur for cutting grooves, burnisher with slightly flat side, burnisher (top has a slight angle for "massaging" the welded surface), graver for cutting grooves
This is a double-walled fine silver waste bowl that had many dents. The handles had disconnected from the rim because they were lead soldered. I had to disassemble the inner and outer bowls, remove the dents, reassemble with lead solder, repatinate, and hand polish.
I decided to make a stronger connection where the handles meet the rim, so I welded the dragon toes with sterling (silver soldering would have obviously melted the lead solder holding the two bowls together).
8/9/2012: Welding extremely thin sterling
Below is a close-up of a weighted candlestick. The customer didn't want a complete restoration, but to simply repair the stem-to-base connection without removing the dents. The candlestick material was only about .004" (.1mm) thick. I was able to weld the split closed with .010" (.25mm) sterling filler wire using the following settings:
What's amazing is that I didn't have to empty the pitch to perform a successful repair. Upon completion of the weld, I remelted the pitch which filled in any voids around the repair.
7/26/2012: Protect alligator teeth from marring your work.
1. Grind down the jaw teeth
7/19/2012: Wallace Sterling Golf Trophy working large
Filling in dents and welding cracks. I have the trophy sitting on a rolling pneumatic table that can be height-adjusted. I constructed the table out of an old office chair, removing the seat and replacing it with a piece of plywood.
5/30/2012: Sterling Kiddush Cup
This Kiddush cup was made from very thin material. I reshaped the torn area which extended 3/4 of the way around the stem. I then brought together both sides of the split and welded them together. All voids were filled by welding with sterling wire for a perfect color match. I straightened the stem and leveled the bottom and top rims. I then removed the dried polish and performed a very light hand polishing.
5/10/2012: Welding Objects That Flex
5/5/2012: Argon Consumption
There are many things about the PUK I enjoy. One of those features is the very low argon consumption compared to other systems. I find that I can perform 99% of my welding using only 1.5 liters per minute (lpm).
5/5/2012: Sterling & Amber Ring
This is going to blow you away! A friend came to me with an amber and sterling ring. The amber was glued into the setting with decorative wires above, only 1/16" from the amber. As you can see below, the wires had come apart. So, I couldn't remove the stone, and was forced to weld the wires back together (I would have chosen to weld them regardless of whether or not the stone could be removed). If I had used a laser welder and missed the mark, the stone would have fried. But first, I wanted to try the technique I was about to use on a sterling jump ring surrounding a piece of plastic. It worked - no harm came to the plastic. Here's the procedure I used...
The wires were pried open and the silver solder removed.
The wires were then sprung back together. As a precaution, I slipped four layers of index card stock between the wires and the amber to prevent the stone from burning.
Below are the wires reattached with sterling filler wire. I used the filler setting with 1.5ms and 30% power.
4/16/2012: Sterling Box Cover
This box cover's four corners were all split. I used sterling filler wire on the inside and outside, then compacted the material from the outside to remove any porosity. What appears to be a corner split in the third image is actually a reflection
This bracelet wasn't the thinnest piece I repaired with the PUK, but it did present a new issue: How would pulse arc welding hold up to constant bending?
This was the procedure I used:
The split was thoroughly cleaned, then beveled on the back side. I used .010" sterling filler wire and over-filled, spreading and smoothing material on either side of the break to strengthen the area. If I had not added additional support, I would see this piece back in my shop in a short time. I didn't totally compact the filler metal as it would have become too brittle with the possibility of the split re-opening. I decided to simply burnish the surface to remove any surface porosity. This left the filler material a bit more flexible.
12/30/2011: Sterling Casters
Someone had the clever idea to engrave these 1730 caster bodies with "salt" and "pepper." (The tops were left off to show a larger area of the engraving.) Engraving the function of these pieces is certainly not something I would have done, but to each his own. Since the silver was too thin to remove by filing, I used the PUK and sterling wire to fill it in. When I photographed the "after" image I had not yet polished the bottom sections of the casters.
12/11/2011: Sterling Cut Glass Jar Cover
This 5½" Wallace sterling cut glass jar cover was stamped and spun out of extremely thin material. The image on the left shows light coming through three areas of a flower as well as other areas on the piece. These areas were worn through from over polishing. The edges of the open spaces were the approximate thickness of a piece of tin foil (.001"). The PUK worked beautifully, and I used .25mm sterling wire for a perfect color match.
11/18/2011: Heat-sensitive Stones
Question from jeweler: I recently purchased a PUK Pro welder and am contemplating a retipping of a Tourmaline. I've completed several successful repairs upon Diamonds and Rubies but haven't worked on softer, heat-sensitive gems. Can you share any advice or point me in the direction of any technical material?
Answer: Tourmalines are inherently fragile stones. Having said this, there should be no problem rebuilding a prong. Firstly, it is advisable to try this technique on a practice setting holding a faceted glass "stone." Use 36-gauge annealed wire (.005") and the lowest possible power setting on your PUK when welding. Welding from the outside of the setting (don't let the electrode pass over the glass), build the prong straight up with the filler wire. When you're happy with the height of the prong, finish it and gently push it over the glass.
11/4/2011: Standard Sterling & Argentium
I did a comparison test using .030" (0.76mm) sheet standard sterling and Argentium. I used the gap mode with 6ms and 45% power for both alloys. The standard sterling (left) had smaller and slightly rougher welds than the Argentium, and demonstrated more oxide formation. The actual weld diameter sizes were .030" (0.76mm) for standard sterling, and .040" (1.02mm) for the Argentium. Dropping the power to 30% when welding the Argentium gave the same size diameter weld as the standard sterling.
Conclusion: Argentium gave a cleaner and smoother weld with 30% less power consumption as compared to standard sterling.
Standard sterling Argentium
Today I experimented with welding metals other than the sterling I normally work with. I cut some lead-free pewter sheet that was .040" (1.02mm). I filed the edges of each sheet 90 degrees to make a butt joint. I then used the PUK's gap filler mode with a setting of 6ms and 35% power, running down the center of the joint and overlapping each weld 50% I welded the top and bottom of the joint, with sheet penetration of over 50%. I then sawed through the joint and used 1200-grit silicon carbide paper to see if there were any gaps and found none. I folded the sheet on the joint in half from front to back, then back to front, and found no stress cracking. I continued the folding back and forth which eventually resulted in joint failure. This was because the joint was more brittle than the rest of the sheet. The same failure would have resulted if I had used pewter solder.
Since I was in an experimenting mood, I used the same PUK settings and welded the pewter to the aluminum backing of a safety edge blade with excellent results. The aluminum was then welded to the steel blade - this, too, was successful.
10/15/2011: Gorham Sterling Match Safe (shown repairing the seam only)
9/22/2011: Sterling Pie Server
This problem normally would require me to remove the plaster from the handle making sure it's perfectly clean before brazing. I would then have to go in with a scraper and clean around the split to guarantee a successful brazing job. Most handles I repair contain pitch which would have to be fully emptied so to not contaminate the joint (Arc welding and laser welding would have produced enough localized heat to melt the pitch, contaminating the seam.) For this handle, I experimented by removing only the plaster that was attached to the underside of the ragged split (approximately 2" in length) and left the remaining plaster in the handle. Also, I didn't remove the solder from the seam - arc welding and laser welding technology normally wreak havoc when working with solders, but I was curious to see if the PUK would give me a different outcome. I cut a piece of annealed .005" sterling sheet and used it as a shim in the split, exposing about a 1/16" above and below the surface. I then clamped the two sides together and began welding using the PUK's gap filler mode. Positioning the electrode on the top edge of the shim, I was able to melt and "push" the sterling down into the split, successfully filling the most of the void. This process is completed within milliseconds. I then used .010" annealed sterling wire to fill any remaining voids. The end result displayed absolutely no porosity and was undetectable. There was no firescale or firestain to remove, no patina to be reapplied, and a seam that would never split again.