| Stop-flo™ No.1 and Stop-flo™ No.2 are two stop-off or ‘parting’ compounds formulated to prevent the flow and wetting of molten brazing filler metal across the surface of a component during the brazing process. They can be applied to components to ensure that filler metal does not flow into holes, grooves or into threaded areas for example. Both products are made from finely ground chemically inert and thermally stable compounds. Stop-flo™ No.1 is the general purpose product designed for use on most common engineering materials. Both products are suitable for vacuum furnace, controlled atmosphere or air brazing processes. Residues of Stop-flo™ No.1 or No.2 before and after brazing are best removed using a water wash. Stop-flo™ Paint Stop-flo™ No.1 is a water-based paint that can be applied to components by using a brush. The normal drying time is approximately 15 minutes. The paint can be diluted with water by up to 25% giving a drying time of approximately 20 minutes; or up to 25% with a water: denatured alcohol (methylated spirit) 50:50 mix by volume – giving a 15 minute drying time.Stop-flo™ No.1 paint is suitable for vacuum brazing operations as well as for brazing in air in silver brazing, copper phosphorus or copper based brazing processes. It will work at temperatures exceeding 1600°C. It is recommended that the product be stirred thoroughly before use. Stop-flo™ No.1 Paint is supplied in 500gm pots. Stop-flo™ Paste Stop-flo™ No.1 and No. 2 pastes consist of the stop-off compounds held in an organic binder and thinned to a suitable consistency with a small quantity of a low alcohol base thinner. The pastes can be packed in syringes or cartridges allowing the paste to be dispensed automatically. Stop-flo™ paste can be placed precisely onto components using an automatic dispenser. This allows the paste to be positioned in narrow lines on components. Normal drying time is 15 minutes. No remixing or stirring of the paste is necessary before use. The binder in the product decomposes well below brazing temperatures and leaves no residues. Stop-flo™ No.1 or No.2 pastes are supplied in 45gm syringes (30cc), 110gm cartridges and 500gm pots. Stop-flo™ Tape Stop-flo™ No.1 and No. 2 are available as adhesive backed tapes. This allows the operator to cut the Stop-flo™ tape to a desired shape and stick it to the component being brazed. One advantage of this product is that the stop-off compound can be applied to vertical surfaces without any run-off. The binder and adhesive in the product decompose well below brazing temperatures and leave no residues. The binder burns with a yellow flame and there is no noticeable odor or fume when a torch or burner is used as the heating method. Information provided by Johnson Matthey Metal Joining |
