Forney37025 Aluminum Welding Flux, 4-Ounce

Trusted brand. Worked perfect for the out aluminum brazing project. The powder is convenient so we can make what we need and store the rest. It should last a long time. Came sealed and powder looked fresh no clumps

Super easy to use and works well when welding aluminum

I'm brazing some aluminum pieces to make a heatsink for my computer. I used Bernzomatic AL3 brazing rods, which does not require the use of flux. I had mixed results with it: sometimes the bond was strong and other times it peeled off when pried with a pair of pliers. I definitely got better results when I scrub the molten metal with the base metal with a stainless brush. It clings better as opposed to simply letting the molten metal float on top of the aluminum oxide layer. The problem is the brush eventually clogged with metal. So I turned to this flux in order to eliminate the brushing.Specs on Forney's website state this is torch brazing flux despite the name. The ingredients are Lithium Chloride, Zinc Chloride, Potassium Chloride, Sodium Chloride, Sodium Fluoride. This is the exact same flux as Superior No. 20. with working temperature of 345°C-690°C. The AL3 melts at 400°C.I've done a few test pieces with the flux and so far so good. I still need to refine my technique but the bonds have been adequately strong. I mix a very small amount with water and then apply. The consistency is that of lemonade. This way the torch doesn't blow the powder off. When the water has boiled off, a layer of dry white flux coats the base metal. It then turns to a clear liquid and quickly to grey. The grey color is the aluminum oxide lifting off. As you continue to apply heat the grey particles gets displaced and you start to see the shiny aluminum and that's when you can apply the brazing rod or solder. Tin/Silver solder works well with this flux.I think it works best with not too much flux and allowing the heat to dwell as the flux does its cleaning. Torch distance is critical as to not melt the base metal. The problem that arise is when there's too much flux a thick layer of the grey particles develop which creates a barrier for the braze. You would have to then manually displace this layer to expose the shiny metal underneath before laying down the brazing rod or solder. Sometimes the braze or solder simply beads. This means the base metal is not hot enough. Simply continue to apply heat slowly as the flux transfers the heat. When the temperature is right and a shiny base metal is exposed you'll see the bead collapse and thoroughly cover the base metal. It's neat to watch.

Seems to help with aluminum brazing. A lot of product in container. Will last a long time.

Ordered this with minimal instructions and eventually trashed the jar... 3 stars because shipping was great...

Good. What I was looking for. Good price.

This stuff is great. A little powder mixed with very little water to make a runny paste and painted on parts with a flux brush is all you need. If the piece has organics that need removal or if oxide has not been sufficiently removed, the paste will not spread evenly and stay where you put it. That's a very good indicator that you have not prepared the surface sufficiently and you will not get a good weld. If the surface is good to go, the flux reduces the surface tension of the melted welding material and allow capillary action to pull it into, around, under the seam. Heat it slowly to remove the water then heat until it darkens and becomes a liquid and you are at the correct temp for welding.If you have never braze welded aluminum before, I strongly suggest watching a few YouTube videos first. See what people do wrong and what they do right. Most failures are from not preparing the surface and many could be avoided by using the proper flux.

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