Surface Coating of Iron Castings

The most of iron castings need surface coating to prevent rust. According to the different functions, there are many types of surface coatings. According to our experience of Dandong Foundry, we briefly introduce some main coatings for castings.

1. Primer anti-rust painting

In order to prevent the rust during shipping, normally, iron foundries will paint the anti-rust primer painting for iron castings. These paintings are very normal, so the prices are very low, it is about 30 USD/ton based on the total weight of castings.

2. lead-free (nonleaded) anti-rust painting

Normal primer painting has some content of lead, which will cause the pollution to the underground water. Therefore, some iron castings need lead-free painting. Lead-free painting is more expensive than normal primer painting, so they are not widely used except for the special uses.

3. RAL painting

RAL painting means the painting lives up with the RAL standard and requirement to the colors. You need to buy these painting from professional painting suppliers. Therefore, their cost is higher than normal painting. RAL painting is for the finish painting, not for primer painting.

4. Zinc-rich primers

Zinc-rich primer paintings have many advantages, such as quick drying, good physical properties, good anti-heat property and can be mixed to proper colors. Of course, zinc-rich primers are very expensive, it is about 150 USD/ton. So, it is not commonly used.

5. Polyurethane Coating

PU (Polyurethane) Coating has good durability and good surface flexibility. Its cost is about 150 USD/ton based on the normal casting weights. Not commonly used.

6. Electro Galvanizing

This kind of galvanize is also normally called as zinc plating. It is about 80 to 120 USD/ton according to the difference of surface areas. Electro galvanizing is commonly used for the high anti-rust requirements.

7. hot dip galvanizing

Hot dip galvanizing is also called hot galvanizing, or called HDG, which is a kind of chemical galvanizing process. HDG has very good anti-rust properties, it can prevent the iron castings from rust for several years in the sea water. Since HDG has pollution and can consume more zinc, so its cost is high, it is about 230 USD/ton.

8. heat resistance paint

heat resistance paint is also called as fire-resisting paint, which is normally used for the stove parts. Since they need to resist hundreds of degrees heat, so they are more expensive than normal painting. It is about 220 USD/ton. Not cheap!

9. asphalt paint, bituminous paint

Bituminous paint is also called as asphalt paint, which is usually used for the pipe lines and fittings, or marine parts. Normal bituminous paint is not expensive, which is almost same as the normal anti-rust painting. However, many overseas clients will require the environmental bituminous paint. So, this kind of paint will be more expensive, it is about 60 to 70 USD/ton.

Besides, there are many other surface coatings for iron castings, such as electrophoresis coating, chrome-plating, powder coating, emulsion paint etc. We can not list all of them herein.

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