Aluminum joints made with fluxless Alumite solder have been evaluated by Bell Laboratories and found to be permanent, corrosion resistant, and stronger than joints made with other solders. To solder aluminum, the invisible oxide film must be penetrated by the solder to obtain metal to metal bonding. This can be done simply and effectively without chemical flux by using Alumite. It is only necessary to heat the area to be soldered to a temperature that will melt the end of the solder stick as it is drawn across the heated aluminum surface. The solid end of the solder stick first punctures and loosens the oxide layer and allows the solder to flow underneath. This is known as "tinning the surface".

Many types of repair and construction are possible using this fluxless technique; however, the aluminum surface must be accessible to stroking by the Alumite solder rod. The solder will not flow by itself into a capillary joint. To promote capillary action, companion flux - Kapp Lunar Flux - is required.

ALWAYS USE A NEUTRAL FLAME!

ALWAYS KEEP THE FLAME IN MOTION!

ALWAYS COOL SLOWLY!

NEVER PLUNGE THE HEATED PARTS INTO WATER!

T - Joints

For maximum strength, tin both members as described above and bring together. Heat the parts and flow a fillet of solder into the intersection. Fillets are made by running the solder stick along set-up members where contact is desired. Let the heat from the members, NOT THE FLAME, melt the solder. Run the solid end of the solder stick through the molten fillet to remove any trapped oxide. In many cases, adequate strength can be obtained without pre-tinning. However, when the members are not pre-tinned, the fillets alone support the joint load, as the members are not joined to each other, but only to the fillets.

Butt Joints

Ends are beveled and brought together. Follow the tinning procedure, stroking both beveled surfaces of the joint with Alumite.

Lap Joints

Parts can be tinned and slid together while the solder is still molten. Alternatively, a generous fillet of solder can be applied to the edges of the lap joint, making sure of tinning by running the stick through the molten solder.

Mitered Joints
in Windows, Doors, Screens, Frames

Members should be solidly jigged. A neutral flame is played over the joint area until the Alumite will melt when drawn across the joint. Make sure of tinning action by drawing the solid end of the solder stick through the molten solder deposit. After tinning, the joint may be built up and finished as desired. These joints are stable in high humidity and have remained in perfect condition after many years of exposure.

Repair and Change Design of Aluminum Match Patterns and Dies

The Section to be worked is cleaned by filing or grinding, then tinned by heating the aluminum to a temperature that will melt the solder stick rubbing the surface. WHEN TINNING, THE ALUMITE STICK SHOULD ALWAYS BE KEPT OUT OF THE FLAME. Build up the material with a soft flame. Pre-heating the entire match plate of the die to approximately 600°F facilitates this procedure.

Welding Zinc Based Castings

Remove any plating, natural oxide, or foreign matter from the surfaces to be joined. "V" out the fracture and set up the job solidly. Use #1 or #2 tip to preheat the area surrounding the fracture. The weld is then made by heating the fracture directly with a neutral flame until the SURFACE of the base metal can be broken by touching it with the Alumite rod. KEEP THE ROD AWAY FROM THE FLAME AS MUCH AS POSSIBLE WHEN STARTING THE WELD. Continue welding the fracture by puddling the solder in the base metal. NEVER PLUNGE INTO WATER TO COOL. Finish as desired.

Welding White Metal

Clean plating and scale from the surface to be welded. "V" out the fracture and set up the job solidly. Preheat generally with a neutral or acetylene flame. Heat directly until the parent metal begins to melt, then dip the solder rod in and out of the molten puddle to the desired buildup. NEVER PLUNGE INTO WATER TO COOL. Finish as desired.

Repairing Stripped Threads

Drill the old threads out over size, so that when the new fillet is added all the drilling and tapping will be done in Alumite. This will make it easier to work with and will increase strength. After drilling, heat the base metal from the bottom of the hole up. Tin the rod into the wall of the hole, beginning at the bottom and work up. Fill the hole, cool, drill and tap as needed.

Excellent Capillary Action on Aluminum
Using KAPP LUNAR FLUX

For blind joints, complicated assemblies, or automatic and furnace soldering, where Alumite can not be manipulated to remove oxides, KAPP LUNAR FLUX is required for capillary action. The fluxing action is very rapid, and when the correct temperature is reached, the solder will melt and be drawn under the oxide layer.

This capillary action is so pronounced that it is possible to draw the solder between two pieces of aluminum, even when both pieces are in a vertical position. After pieces have cooled thoroughly, flux residues must be removed with hot water.