Prip’s Flux

Prip’s Flux is a fire scale preventative.  It will not always prevent fire scale – but, it helps a bunch.

Safety – Wear a particulate (N95) mask when measuring and pouring the chemicals as they are powders and the dust will enter your lungs.

The Recipe:

                                                                                   

1 quart or 4 cups of  water

½ cup or 4.23 ounces or 120 grams boric acid (available at pharmacies)

2.822 ounces or 1/3 cup or 80 grams TSP (trisodium phosphate – available at hardware stores)

2.822 ounces or 1/3 cup or 80 grams borax (available at the grocery and probably, the hardware store.  I use 20 Mule Team Borax, which is 99% Borax and 1% trace elements.)

This is generally a 3:2:2 mix with 3 being the boric acid and 2 the TSP and Borax.

Boil mixture, stirring – adding more water if necessary, until all powders are dissolved.

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It is important to spray this flux onto WARM metal.  So, heat briefly with the torch and spray until you have a fine layer of the mixture and there are no spots of bare metal visible.  You can apply your soldering flux and solder before spraying or after or not at all.

You can also dip the piece into the mixture or brush it on.  These methods are not ideal but, better than nothing.  When using the dipping method or brushing method, heat until the flux dries evenly.  Your goal is to just dry the flux and not to over or under heat it.  With overheating you will see it change color (yellow or brown color) with under heating, it will remain liquid in spots.  The Pripp’s should be white when heated properly.

When the Prip’s is dry,  apply your soldering flux to the join being soldered and then the  solder.  Theoretically, you shouldn’t need soldering flux but, I often use it.

The flux will re-crystallize and can clog sprayers.  You can either re-heat the flux or use a mouth atomizer to aid in application. Another method is to let the flux sit for  a few days, until  crystals begin to form.  Pour off the liquid into the spray container and leave the crystals behind in the storage container.  If you are using a spray bottle or an air brush and the sprayer is clogged, transfer the mixture to another container and then thoroughly clean the spray container and spray mechanism with water – removing all crystals. Then pour the solution back in. If possible, store the spray mechanism separately so, that crystals don’t form in the hose or alternately, pour the unused portion of flux back into the storage container when you are done and rinse the sprayer well – give the spray mechanism a few pumps in clear water to rinse out any of the solution.  This will avoid crystal buildup and blockage.

You can read more about Prip’s flux in Peter W. Rowes article at Ganoksin.

  Mouth Atomizer  Mouth Atomizer