Trouble with Flux coat before transparents on fine silver

I use a champleve border on my cloisonne enamels. I fire japanese leaded transparents and opals, so I generally fire over g110 for silver flux on fine silver. My borders are 20 ga (.81mm) and my pieces are slightly domed- i don’t have a lot of height at the borders so I want to lay down a very even coat of flux, just enough to prevent discoloration. If I sift a dry coat (no fines), even a light one, it collects at the edges. If I apply a coat of wet pack it also moves to the edges in firing. That leaves me very little depth at the edges to add color and the flux tends to move up the sides so it creates a thin colorless barrier at the borders.
Anyone have any tips on applying a light even coat of flux without it bunching up at the sides?

Try under-firing the flux. You want a sugar coat which is the point where the grains have adhered but haven’t melted yet. Then when you add your wires, under-fire to orange peel. The wires will sink in enough to adhere. Then when you fire your cells the flux will melt and it should reduce the amount of pooling at the edges. Of course, there will always be a little pooling because of the downhill slope but this approach should reduce or eliminate the colorless border.

And another little trick: before you sweat solder or fuse your border, under file the edge enough that you don’t see it when looking down from the top.

And a possible factor may be in the application of the klyr-fire. Use an applicator which give a very fine spray, hold the piece parallel to the floor and at arm’s length, and spray above the piece. The droplets will fall onto the piece and be in a much thinner layer than if you spray toward the surface. Thicker klyr-fire will run to the edges and capture more flux grains. I find the Crown Spra-Tool gives a very fine droplet. https://www.amazon.com/s?k=crown+spra-tool+kit&crid=11S4HLIUR9RBP&sprefix=crown+spra-tool%2Caps%2C159&ref=nb_sb_ss_ts-doa-p_2_15 Get additional air cannisters at office supply.

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Hi Vera,
Thank you. I decided not to use klyr-fire this time around - just to keep things clear. Do you think it helps to keep the flux from drifting towards the edges? If so I may revert to using it- I must say that my thick flux coats were nice and clear. Hadn’t thought of atomizing the spray to give a very light coat. That sounds like it is worth a try.

Regarding the undercut of the border- I just recently read of this technique in regard to sweat soldering two metals together - keeping the solder from forming a visible meniscus edge of solder at the seam. I immediately thought- hmm- this could be a good solution to reduce flux build-up at the edges. Definitely worth a try.

Finally- under firing until I get some wires on. Another good idea. If the flus stays in the cloisonnes it won’t be flowing to the edges.

The pieces in question are of significant size that I ordered some diamond grinding bits and will be working to remove the build up at the edges. I have found that these attempts at recovery are often an exercise in futility, but I will try. Too bad that Hydrofluoric acid is so nasty and deadly.

Thanks again- Kirk

Just noticed that I failed to mention that the fine mist of Klyr -fire would be followed by sifting a light coat of flux, and maybe repeating spray,sift and then fire to sugar. The flux will not build up on the edges unless you have excess Klyr-fire there to hold excess grains from excess sifting. And firing to sugar means that it doesn’t slide to the edges because the grains haven’t melted. Hope that clarifies.

Vera, The link to Amazon you posted does not seem to be available on Amazon. Can you check your URL and correct it? Can’t find the product on Amazon.

It’s the Crown Spra-Tool by Aervoe. Here is a picture of the packaging.

Hi Vera, Thanks again. I have a similar aerosol sprayer called Preval. I will try it with the klyr fire, a light sprinkle of flux and a fire to sugar stage.I think I will go right to wires after that and If I need additional protection for reactive enamels - I will do a color/ shading undercoat of non-reactives rather than another coat of flux- at least I get something going design wise near the bottom.

I received some sintered diamond grinding bits from Hi-Tech Diamond. I had never used them before but with constant water dipping and my foredom - I was able to remove 100% of the flux coat. The pieces are in good shape. Removing only some of the flux was impractical because once the diamond cut the enamel it left embedded fines in the surface. I was very pleased- the diamond grit also left a very interesting pattern on the silver that I am going to take advantage of.surf

I forgot to mention that although I hadn’t use klyr-fire I had used distilled water with a touch of surfactant- I am sure it flowed to the edges.

I’ve learned a good lesson, we’ll see how I do when I reflux these.

Thanks