1. How does galvanizing protect steel from corrosion?
Zinc metal used in the galvanizing process provides an impervious barrier between the steel substrate and corrosive elements in the atmosphere. It does not allow moisture and corrosive chlorides and sulfides to attack the steel.   Zinc is more importantly anodic to steel - meaning it will corrode before the steel, until the zinc is entirely consumed

2. Does the galvanized steel coating of zinc resist abrasion?
The three intermetallic layers that form during the galvanizing process are harder than the substrate steel and have excellent abrasion resistance.

3. What causes wet storage stain and how can it be prevented?
Zinc on newly galvanized steel is very reactive and wants to form zinc oxide and zinc hydroxide corrosion products that eventually become the stable zinc carbonate.  When galvanized steel is tightly stacked or stored in wet boxes that don't allow for free flowing air, the zinc forms excessive layers of zinc hydroxide, otherwise known as wet storage stain.  Most wet storage stain can be easily removed with a cleaner or nylon brush.  To prevent wet storage stain, store galvanized steel indoors or block it so that there is ample free flowing air between each galvanized article.  

4. Why do galvanized steel appearances differ from project to project and galvanizer to galvanizer and is there any difference in the corrosion protection offered by the different appearing coatings?
The steel chemistry is the primary determinant of galvanized coating thickness and appearance.  Continuously cast steel produced by the steel companies has a wide variety of chemistries, thus the different coating appearances.    There are several different additives that galvanizers may put in their zinc kettle to enhance the coating appearance by making it shiny, spangled or matte gray. The appearance of the coating (matte gray, shiny, spangled) does nothing to change the corrosion protection of the zinc coating.  

5. Why would you want to paint over galvanized steel?
Called duplex coatings, zinc and paint in combination (synergistic effect) produce a corrosion protection approximately 2X the sum of the corrosion protection that each alone would provide.  Additionally, duplex coatings make for easy repainting, excellent safety marking systems, and good color-coding.  Painting over galvanized steel that has been in service for many years also extends the life of the zinc coating.  

6. Isn't galvanizing more expensive than paint?
Depending on the product mix, square feet per ton, and condition of the steel surface, galvanizing is often less expensive on an initial cost basis.  However, as with any purchase, the lifetime costs should be considered when making a project decision on the corrosion prevention system to utilize.  And, with galvanizing, the life cycle cost, i.e. the cost per year to maintain, is almost always less than a paint system.  Paint systems require maintenance, partial repainting and full repainting several times over a 30-year project life.  The costs can be staggering, making the decision to paint a costly one in the long run.

7. What if the article to be galvanized is larger than the dimensions of the galvanizer's kettle? Can it still be galvanized?
Galvanizers can progressively dip such a fabrication or article of steel.  They dip one half in the molten zinc bath, remove it, turn it around or over and immerse the other half in the zinc.  This method is often erroneously referred to as 'double dipping'

8. Is the zinc coating's thickness consistent over the entire piece?
Coating thickness depends on the thickness, roughness, chemistry, and design of the steel being galvanized. Any or all of these factors could produce galvanized coatings of non-uniform thickness. Members of the American Galvanizers Association galvanize to ASTM standards, which define minimum average coating thickness grades for various material categories.

9. What can I do to minimize possible warping & distortion? Is it possible to determine - prior to galvanizing - which pieces might be prone to this occurrence?
Minimizing potential warpage and distortion is easily done in the project's design stages by selecting steel of equal thicknesses for use in every separate subassembly that is to be hot-dip galvanized, using symmetrical designs whenever possible, and by avoiding the use of light-gage steel (<1/16" / 1.6 mm). Some structures may benefit from the use of temporary bracing to help maintain their shape and/or alignment.

10. Can I paint right over the galvanized coating? If so, what procedure should be followed?
Galvanized coatings can be easily and effectively painted, not only for aesthetics but also to extend the structure's service life. The age and extent of weathering of the galvanized coating dictate the extent of surface preparation required to produce a quality paint system over galvanized steel. ASTM D 6386, Practice for Preparation of Zinc (Hot-Dip Galvanized) Coated Iron and Steel Product and Hardware Surfaces for Painting, should be consulted for suggested surface preparation methods for galvanized coatings of varying ages.

11. What does it mean to "double-dip" steel?
"Double-dipping" is the progressive dipping of steel that is too large to fit into the kettle in a single dip. Double dipping cannot be used to produce a thicker hot-dip galvanized coating.

12. What is the reason for incorporating venting & drainage holes into a project's design?
The primary reason for vent holes is to allow otherwise trapped air and gases to escape; the primary reason for drain holes is to allow cleaning solutions and molten zinc metal to flow entirely into, over, and throughout the part, and then back into the tank or kettle.

13. What size is your galvanizing kettle?
Silver City Galvaizing has two separate galvanizing kettles. The large kettle, is 31’ x 5’4” wide and 6’ deep. The second kettle at Silver City is used for smaller threaded material and is 8’ x 3’6” wide and 5’ deep.