Recommendations for soft soldering of Prelaq PLX

By soft soldering, hot-dip galvanized steel sheet can be jointed together. By heating the sheets to 180- 230°C and adding a soldering material of tin/lead, the sheets are jointed to a water tight and strong overlap joint.
The paint coating has to be removed on both surfaces before the soldering work.

The material that is to be soldered, is built up of a steel core with a layer of zinc coating (0,025 mm) and a paint coating (0,05 mm). On the reverse side the PLX material has a zinc coating and a thin paint coat (0,010 mm)

Material   

Paint remover, Chemical
Prelaq Touch-Up Paint
Cleaning detergent
Water
Scotch Brite sponge
3M Sanding sponge 

Soldering equipment

Soldering material of tin/lead (50/50 or 60/40)
Flux
Burner with copper bit for soft soldering
Paint brush

Working stage 1 – Removal of the paint

Before soldering, the paint must be removed from both surfaces that should be jointed.

The paint layer can be removed in two ways: By using a chemical paint remover or by carefully abrade away the paint with a special Strip Disc. By using the later method care should be taken not to abrade the thin zinc layer. The first method is shown here.

Remove the paint - chemical method (method 1)

1. Cover the surfaces that should be soldered with the Paint remover.

2. Wait for approx. 20 minutes

3. By using the spatula (sharpened), remove the paint.

4. Use a Scotch Brite sponge to remove the remaining paint

Working stage 2 – Soldering

1. Use a paint brush to cover the cleaned surfaces that should be jointed with the flux. The flux makes the solder to flow out.

2. The clean and prepared surfaces should be put together with an overlap of at least 10-20 mm. See that there is no gap between them.

3. By the help of the burner with copper bit, heat surfaces to receive solder along the overlap edge. The solder will penetrate and fill the gap between the sheets.

Working stage 3 – Cleaning and painting

Before painting, the surface should be cleaned with water and a mild wash detergent. When the surface is dry, paint the unpainted parts with a brush using Prelaq Touch-up Paint.