What are the 7 Stages of Chemical Stripping?

“7 stage chemical stripping is known as 7 Stage Phosphating”

Pre-treatment is the process of chemical preparation of various types of metal and aluminium prior to the application of a Powder Coated surface finish. This chemically converted layer adheres strongly to the item's surface to provide an effective key for the finished Powder Coated product.

The 7 stages of this process are as follows:

Tank 1: Cleaner:

In the tank is a product called Alka-Soak L T.
Heavy-duty alkaline cleaner for iron and steel. Formulated to remove greases, oils, smut, and stearate residues. Suitable as a soak degreaser prior to phosphating, electroplating and vitreous enamelling.

Tank 2: Water Rinse:

Clean water washes off the Alka-Soak and neutralises pH on the metal surface.

Tank 3: Acid Pickle:

This tank consists of a blend of Commercial Sulphuric Acid and Acid Wet. The primary function of this tank is to remove all scale from the surface. I.E., welding scale and rust.
The Acid Wet aids the acid in removing the scale by assisting the acid to “wet” the surface.

Tank 4: Water Rinse:

Clean water to rinse off the acid and neutralise the low pH on the steel surface.

Tank 5: Phosphate:

The product used in this tank is Iron Phos HF. This solution generates an iron phosphate coating on the surface of the metal.

Tank 6: Water Rinse:

Clean water to rinse off the phosphate solution and neutralise the low pH on the steel surface.

Tank 7: Passivator:

In this tank is a product called Passivator P.
PASSIVATOR P is a chrome-free iron phosphating type passivating solution which provides excellent under-paint corrosion protection.

Reasons for 7 Stage Chemical Stripping / Phosphating?

1. Paint Adhesion: The iron phosphate coating acts as an absorbent to allow the paint to “grab” onto thereby giving superior adhesion.

2. Under-paint corrosion protection: If the outer covering of paint was scratched, the steel would rust. The entire surface runs the risk of rusting under the paint and creating blisters. With an iron phosphate coating, the rust would be contained to only the scratched area. Under-paint corrosion would be reduced, and blisters avoided.

Dynamic Steel Coaters

Registration No: 2017/083249/07

Tax No: 9241655225

Vat Reg No: 4870279496

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010 446 3888

083 567 2965

083 548 1251

083 567 2965

083 548 1251

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