When not using syringe on the bench for several days remove the needle and replace the tip cap on syringe. Store syringe in a cool place. Save the needle for further use. Store the needle with the syringe to prevent cross contamination with other paste solders.

Keep the needles clean. If the needle clogs it can be unclogged with a fine wire, or cleaned in an ultrasonic cleaner.

1) Prepare the joint by removing all oil, grease, polishing compound and excessive oxides from the joint area.

2) Joint clearance (gap) should be as small as possible. The joint should be flat, smooth and free of burrs. The two pieces being soldered should touch, as paste solder will not fill large gaps.

How to use solder paste (image)3) Apply paste to the top of joint. (To prevent excess flow of solder from the needle after applying solder to the joint, pull back on the hand plunger to relieve pressure.)

4) Apply heat to article away from the joint, moving the torch from side to side across the joint to avoid overheating the solder. Allow the piece to heat the paste solder. Do not directly heat the paste solder. (This will cause the paste to “slump” and move away from the joint.) As binder “burns off” and the paste dries you will see the flux spread around the solder. Now move the flame in on the joint area continuing to move the torch from side to side.

5) Remove the flame immediately after solder flows.

6) Pickle with Sparex (R) to remove fire scale and finish the article as usual.