Inclusions in my brazing

[thwangs world]

Evening all

I've been practicing my brazing but I keep getting inclusions/ pits small holes in the brazed joints. I've been told it might be a over use of flux. I'm using normal rods and I'm dipping the rods in flux powder. 

What should I try to remedy this situation please.

Regards Simon

[Hahn Rossman]

Simon-

Buy some good paste flux. I really like the gasflux type B. I don't think you can actually use too much of it! But just cover the joint, you don't have to go crazy.

Hahn Rossman

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[Jon Norstog]

Simon,  I get those too.  Using Henry James' blue flux and low-fuming bronze helped a lot - it is much cleaner.  I use plenty of flux and paste/brush it onto the work instead of dipping the rod. - Keep the puddle warm enough that the crud comes to the top and you see a nice, glistening surface of molten metal.

Some metal/flux combinations are dirt.  Welco 17 flux coated has a lot of virtues but looks is not one of them.  "Nuff said.

jn

"Thursday"

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[Mark Bulgier]

What Hahn and Jon said, plus I think porosity can come from boiling the zinc out of the brass by pointing the flame right at the fillet.  There are several advantages to just laying the fillet smoothly in one go, and not re-melting it.  That should be your goal — I know, not easy at first.  But paradoxically fillets look best when they're laid down fast.  Also less heat put into the joint that way, so a smaller HAZ and faster cooling leaves the steel in a stronger state.

[johnny coast]

If your pits include flux then I actually think you are using too much flux, kind of opposite of what some have said here. You can take a small drill and drill out the ball of crystalized flux. Thin out your flux with water and lay it on a little thinner. You need good heat control to do this.

When it boils it looks different, smaller crispy bubbles, and of course burnt up flux in the area... You can see a copper like color in or near the brass, then you're boiling it. If that's your case, then turn your heat down a little. And yes type B gas flux paste and rod. I've never used the powder, so maybe your set of circumstances are different...