pre-soldering tips

Hinxy

Hinxy

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#1
Usually I try to cast in one piece but need a refresh on pre-soldering. I recall fits that were not perfect. Using alloy Superior from Jensen....PWS solder and Laservest soldering investment.
 
Car 54

Car 54

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#2
If it's a multiple pontic case, I try to keep the cut and solder joint 1 pontic (if you can) from an abutment.
The gap of the cut should be as thin as possible, without the sections binding on each other. Lute it together
with a strong dead wax like Ivoclars pontic wax (it's the light blue/green stuff) or use zap it to lute them
together. Keep pressure on both abutment ends as you let the wax cool, or the zap it totally cure.

Then I like to put some wax under the pontic area and even more to the mesial and distal area so that it won't be in contact with the investment
and will heat more evenly. With the investment I'll put some in the abutments, and make a patty on a piece of plastic or whatever, build up little
mounds where the abutments will seat, let the investment get a little firm (can even use a tissue to draw a little moisture out) and set the bridge
on the patty with the little build ups. Those help keep the bridge from sinking to far into the investment, keeping it up a bit. Then I take a bit of
water to some investment I left in the bowl to thin the investment out just a bit, and cover the abutment units to help keep those more stable during heating.

After it has set, trim any extra investment away so you're not heating up a cow patty (Yippee yay a Cow Patty) burn it out in a oven as per Laservest
investment IFU. Then with the torch heat the solder area hot enough to receive the solder, ideally after it's heated you should be able to hold your
torch on one side and feed the solder in from the other side and it should flow towards the heat, torch side.

Sorry I didn't have to much to say about this subject, as I've just recently joined Brevity Anonymous and am trying to keep it simple....
Yippee yay a Cow Patty :)

 
JMN

JMN

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#3
Usually I try to cast in one piece but need a refresh on pre-soldering. I recall fits that were not perfect. Using alloy Superior from Jensen....PWS solder and Laservest soldering investment.
Torch, electric, or laser?

I used to do torch. Using Whipmix hiheat investment.

Grind a bit to get 'fresh' metal at the joints.
Duralay the parts how you want them with the duralay being everywhere you want metal.
Invest, filling the copings and setting it on a patty margin down. Do not 'sink' the bridge, leave at least 3-5 mm between lowest margin and bottom of patty.
After investment cures, cut a trough on the buccal and lingual of the area to be soldered. You are making a flame guide.
Burnout. Replace your tires and then put the investment in the oven per the destructions
Check the viscosity of your soldering flux, add distillied water as needed.
With a pair of tongs, put the investment brick on a tripod.
Start up your torch and heat the receiving metal to mild glow, waving the flame over the area, do not concentrate yet.
Dip the donor metal into the flux.
Bring the donor metal into the gap and fill while focusing on the gap, then waving, then focusing.
Let sit and then grind in after devesting.

I did this with exactly the metal combination you are using.
 
Car 54

Car 54

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#7
Interesting. That's how I was taught. Maybe I should read a bit more?
Maybe some labs do it differently? But it's how I've been doing it for umpteen years. For me, porcelain to metal noble and high noble metal pre-solder, no flux. For gold crowns and NP, yes :)

Just soldered a 6 unit bridge last week, Argen 45SF with Jensen PWS solder, came out seamless :)

edit: I remember in the days of HN post solder, you needed to use flux to get the solder to flow more easily at a lower temp as to not turn your porcelain into a marble.
 
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Z

ztech

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#8
Just a quick primer on the basics. Flux helps control the formation of oxide on parent alloy. Solder will not flow over oxidized alloy. Parent alloy must be above melting point of solder to accept the solder. If you use the flame to melt solder it will form a ball and rest on the surface. Leave as much parent alloy exposed as possible to allow even heating in the area and to prevent point heat melting. Cover all margins and thin areas of parent alloy to prevent melting of thin portions.

Good luck.
 
JMN

JMN

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#9
And no matter what, if you use flux, you MUST have a ventilated work area. It will mess up your lungs, nasal passages permanently.
 
Hinxy

Hinxy

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#10
Thanks......It's been a long time. It's all beginning to come back to me. 70 years old and my memory is somewhat like a Whiffle ball. It was pretty routine for me for a long time to solder without difficulty but, I was using an alloy with a higher gold content (Jelenko Olympia..). Glad you addressed the flux thing. I didn't recall ever using flux on porcelain alloy and I never did any NP. Always on gold though. Thanks again!!
 
Car 54

Car 54

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#14
Just a quick primer on the basics. Flux helps control the formation of oxide on parent alloy. Solder will not flow over oxidized alloy. Parent alloy must be above melting point of solder to accept the solder. If you use the flame to melt solder it will form a ball and rest on the surface. Leave as much parent alloy exposed as possible to allow even heating in the area and to prevent point heat melting. Cover all margins and thin areas of parent alloy to prevent melting of thin portions.

Good luck.
Maybe that's why it's always worked for me, as I always keep the torch on the solder area (no oxidation) right out of the oven with the solder flowing into the joint, introducing the solder from the other side of the flame, drawing the solder into the heat. Sometime I do have to put the torch to the other side, but with the big tip, it's all in the flame, heat zone as I use a multi orifice tip, it keeps a larger area in the flame, heat zone, than just a little solder tip, in which I would have problems with.

I've usually had worse experiences with flux in causing bubbling, but I guess what works on what metal and the technique used? Flux is also a wetting agent, to help solder flow more easily.
 
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Car 54

Car 54

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#15
Just an additional tip, trick Hinxy, and that is whatever you're setting your patty on as it comes out of the oven (a tripod with a grate etc) if you have some Kaoliner set it on that. It will help to keep the heat in the investment patty and bridge and you won't be fighting losing heat out of the bottom. You'll maintain the heat better with the patty, bridge and solder area.
 
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