Hi Everyone. I wrote up a little thing about Freddy Parr's silver butter. Here is what I posted across the hall. Kind of lug centric but you never know when you mountain bikey types will catch the lug bug, better than swine flu....
Well, early this week. I received a tube of Cycle designs Silver Butter. I gave it a try on some joints on a stainless singer lug set from Richie.
I uploaded some photos to flickr. Link at end of post. It might get a little long.
So, first. What is it? It is a silver bearing paste in a syringe that is suspended in stainless light flux. Some history here. I tried using such a substance in silver work and was not impressed. Didn't seem like there was much silver in it. Didn't do much when you got it up to temp.
This stuff is a lot different, that is for sure. The tube that showed up has as certification paper. On that paper it shows type of silver, AWS and AMS certs and that the density of the product is 4.95 troy ounces per square inch. I looked up the specific gravity of pure silver and did a couple of calcs. This stuff is about 75% silver solder by volume.
I first tried it on a seat tube to bottom bracket. I applied it to the inside of the BB shell with my finger. I have some actual figures of how much later. Then applied to seat tube. Twisted together, fixtured and went to town. Usually I tack, then free braze. I piled up the extra butter along the edge of the lug. I then fluxed liberally with Stainless light flux. I heated up the points to tack and right away the silver flowed and they be stuck.
I took the ST out, checked, started the full braze. This stuff definitely works and works well. It is different, that is for sure. When you first go through the heating stage, at least on the edges the silver balls up into tiny little ball bearings and then a little more heat and the silver begins to show along the edges of the lug. My first attempt I used no filler rod in addition but the little balls where chasing the torch up the tube and down along the lug itself. The penetration of the joint was perfect. Surprising.
Next I did H2O stars and three joints simultaneously. The DT/HT ST/TT BB/DT and chainstays. I measure the weight of the product before and after I used it and the weight of the rod I used. I used 10grm of Butter on 4 joints (total weight of product 84grm) and 13grm of rod for a total of 23 grams or about 3/4 OZ. I say that is pretty good.
Everything brazed up great. Easy. Here are the downers so far, that I can tell. 1st. You have to deal with the butter. This adds some time in placement and smoothing it around and you have to work fast otherwise it will dry out and become hard to handle. Next, brazing is just different. You know how you look for silver along your lug edge or coming out the other side of the lug? Not with this stuff. It just comes out everywhere at the same time and I had a little issue seeing where I may need to fill because it already looked filled, but I had a couple of points that I missed. 3rd. I didn't leave any excess butter along the edges of the tubes on the second try but still, right before full braze, the silver balls up and the little buggers chase your flame around, sometimes running on the outside of the tube/lug and then melting there when you are up to temp.
The silver flash is thin, not a big deal to cope with. 80 grit paper takes it right off, but it does look weird. Brazing is easy, but will take some practice to deal with the differences. Penetration is excellent, that is obvious. I think I used less silver than before or at least efficiently so that is good and brazing is speeded up a touch. I think overall, it is a nice addition. Certainly it guarantees complete wetting of all surfaces. Sometimes in normal brazing you can end up with dams that impede the flow of filler metal. These cannot be seen. I would guess that this is reduced, almost eliminated with Silver butter. I was also impressed by the silver content. You don't think it will do anything and then all of a sudden everything is done. That is neat.
One 3oz tube at this rate should be enough for 30 joints or so. Freddy is adding to the choices we have. I need to practice more. The only negative thing I can say is that I don't love the silver flash, but since I sand and finish so much anyhow it really doesn't matter much. The seat tube in the photo set took a total of 8 minutes to finish to that degree. It certainly is some insurance and I can see how it can speed up brazing. It is something I am looking forward to using more of.
Thanks for reading.
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