Black spots on laser printed bridges!!

Adi

Adi

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Hi
I'm printing metal work in another Lab, sometimes black spots occur, remain after bonding bake, but totally covered with opaquer, and does not effect porcelain bakes.
The lab says it's totally safe but he does not know why it happens, anyone knows?
Screenshot_20220305-090416.png Screenshot_20220305-090421.png
 
rkm rdt

rkm rdt

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metal oxides are the cause.
Sandblast it clean and stop degassing.
Applying opaque to a clean surface solves the problem and save time.
Use that time to clean your bench, it looks like Putin dropped a cluster bomb on it.
 
Car 54

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Why is it green? Hopefully that's not a degassing color? What metal or bonding agent are you using?
I use a slurry of pink and orange opaque modifier for my 1st, opaque degas bake.
My dad does the same thing as rkm suggested.
 
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Affinity

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I wouldnt worry about the black spots, but I would follow the instructions for the alloy. That green oxide is what creates the bond on some non precious alloys, like wirobond c (which says to leave the oxide on for the first bake) . If you blast if off before opaquing, you might have bonding issues.. I would sandblast and degass again and see if its still there.
 
Car 54

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That is wild, I used to use Rex3, which had a nice straw color.
 
Affinity

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Sorry I think I was mistaken, its been forever since I used wirobond c, the IFU does say to blast it off, but I swear I remember that being different, I know the green oxide will actually bleed into the opaque and appear on 2nd and 3rd firings. Im having PTSD just thinking about oxide firings, opaquing and bubbles..
 
CatamountRob

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We used to use Williams W1 a lot, that was oxidized and then sandblasted, but most alloy instructions don’t say that. Some alloys will oxidize when you fire the first layer of opaque but not all of them. D.sign 84 doesn’t oxidize at the D.sign opaque firing temps. I learned that the hard way.
My experience has been that if you don’t see a nice even oxide layer after running the manufactures oxidation firing program, sandblast it and do it again.
 
Contraluz

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Why is it green? Hopefully that's not a degassing color? What metal or bonding agent are you using?
I use a slurry of pink and orange opaque modifier for my 1st, opaque degas bake.
My dad does the same thing as rkm suggested.
The alloy I use, d.Sign 30 and thankfully only once or twice a year, indicates blasting and application of the wash. No degass firing. The green oxide will bleed through the wash, which then can be steamed off easily. After the wash firing there is no oxide bleeding through anymore.
 
Car 54

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The alloy I use, d.Sign 30 and thankfully only once or twice a year, indicates blasting and application of the wash. No degass firing. The green oxide will bleed through the wash, which then can be steamed off easily. After the wash firing there is no oxide bleeding through anymore.

I can't remember what high Pd alloy I used for a short while, gave off a charcoal gray oxide that needed to be blasted off. Terrible stuff, as I would get bubbles through the 2nd opaque firing. Some of those would continue to grow oxides through the proceeding firings. The posted image looks like a green caterpillar. Good luck in not having that affect the shade without heavy opaque masking ;) :)
 
Contraluz

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I can't remember what high Pd alloy I used for a short while, gave off a charcoal gray oxide that needed to be blasted off. Terrible stuff, as I would get bubbles through the 2nd opaque firing. Some of those would continue to grow oxides through the proceeding firings. The posted image looks like a green caterpillar. Good luck in not having that affect the shade without heavy opaque masking ;) :)
High Pd alloys are a mess!

As for CrCo alloys, in my experience, after the wash there is no issue anymore with oxide.
 
Davor RDT

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Why is it green? Hopefully that's not a degassing color? What metal or bonding agent are you using?
I use a slurry of pink and orange opaque modifier for my 1st, opaque degas bake.
My dad does the same thing as rkm suggested.
Yeah . Is green desired oxide color with this framework material ?silver palladium ?
 
Adi

Adi

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Why is it green? Hopefully that's not a degassing color? What metal or bonding agent are you using?
I use a slurry of pink and orange opaque modifier for my 1st, opaque degas bake.
My dad does the same thing as rkm suggested.
it is degassing yes, is it wrong?
you mean I should combine degassing and wash opaquer in one bake?
I use GC bond.
 
Adi

Adi

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metal oxides are the cause.
Sandblast it clean and stop degassing.
Applying opaque to a clean surface solves the problem and save time.
Use that time to clean your bench, it looks like Putin dropped a cluster bomb on it.
he's responsible for no doubt.
 
CatamountRob

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it is degassing yes, is it wrong?
you mean I should combine degassing and wash opaquer in one bake?
I use GC bond.
You should follow your alloy makers instructions.
Some alloys will oxidize at opaque firing temps, but some won’t. No oxide, no bond.
 
Contraluz

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it is degassing yes, is it wrong?
you mean I should combine degassing and wash opaquer in one bake?
I use GC bond.
Not sure about GC bond, but as, I mentioned above, some CoCr alloys indicate no degassing, just wash firing. Then steam off the green shine left on the surface.
 

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