Alloy Resources: Post Soldering Guide

Flux A fluoride based flux should be used. Jensen's Brown Fluoride Flux is recommended for use with all alloys and does an excellent job preventing oxide growth during soldering.
Solder Selection Use the solder recommended for the alloy or, in most situations, any crown and bridge solder can be used for post-soldering.
Wax Design A successful post-porcelain solder connection starts in the design of the wax-up. Surfaces to be joined must be flat, parallel and spaced 0.3mm apart. Vertical and lateral extension of lingual marginal ridges next to the solder joints should be enlarged to provide a greater metal surface to receive solder. This type of design will also provide protection for the porcelain during the solder operation.
Preparation and Assembly Prepare the metal surfaces to be soldered by grinding with aluminum oxide stones, sandpaper discs or rubber wheels. Clean thoroughly to remove any loose abrasive particles. Lute the units together. Wax over the porcelain to protect it from contact with the investment.
Investing and Fluxing Invest in a high temperature soldering or casting investment. The investment block should be small and only the lower third of the case should be embedded. Trim and allow the investment to bench set 30 minutes. Wax can be flushed away wax with hot water at this time. If possible, flux all surfaces to receive solder with a light film of BROWN FLUORIDE FLUX. (Note: Stir flux before each use.) DO NOT OVER FLUX - flux should not come in contact with the glazed porcelain.
Drying and Preheating Place the invested and fluxed case in a room temperature burnout furnace. Gradually raise the furnace temperature to 1000°F (540°C) and hold for 10 minutes. Transfer case to a porcelain firing furnace preset at 800°F (425°C). Flux lightly if previous flux has been consumed.
Soldering Place an adequately sized pre-cut and fluxed post solder piece in position on the connector area. Close muffle door and fire in air at 50°F per minute to the expected solder flow temperature (typically, 10-50°F above the solder's liquidus temperature.) NOTE: To establish the flow temperature run a test on a piece of sprue using the appropriate solder and flux. This is especially important when using a new alloy/solder combination or if the furnace has not recently been used for post-soldering. Open the muffle and check for flow of solder. If the solder has not flowed - flux lightly and increase temperature 50°F. When the solder has flowed, remove the case and bench cool.
Devesting and Finishing When the soldered case has cooled for several minutes, devest and clean. Slight staining of flux on porcelain can be removed by ultrasonically cleaning in an 18% hydrochloric acid solution for 2 to 3 minutes. Shape, contour and polish the soldered areas using standard techniques.
Notes The porcelain manufacturer may suggest a different technique to be used with their particular porcelain. For instance, Creation porcelain users should refer to the Creation Post-Soldering Technical Guide. For more information call Jensen at 800-243-2000.