Originally Posted by
unterhausen
Thanks Dave, your posts are always appreciated. I think the black on the outside of the tubes is paint, the first picture is post-brazing and it looks pretty clean. The inside of the tubes look exactly the same though, and I suppose it's unlikely that they were painted.
Exactly - I'm more thinking of the surface of the head tube inside the joints and inside the top and down tubes - pretty darn black. The common reason for this is either that the tubes were still covered with oil and not enough flux was used or it was clean and well fluxed and it was way too hot. Any way one cuts it the blackened stuff is not good.
Dave