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hong  
#1 Posted : Saturday, November 27, 2010 5:36:57 PM(UTC)
hong

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In hot dip galvanizing components are immersed in molten zinc. As they are withdrawn, the zinc cools and forms a coating of zinc on the components. Strictly speaking, the term should be hot dip zinc coating instead.

Electro-galvanizing or 'zinc electroplated' means components are immersed in an aqueous bath, and electricity is used to induce anodes of zinc to dissolve in the aqueous solution, transport the ions, and electroplate them onto the components.

The principal function of both processes is corrosion resistance. Galvanized steel can last for many years if other means are maintained, such as paint coatings and additional sacrificial anodes.
In spite of the protection, rusting will be inevitable, especially due to natural acidity of rain.


Differences between Hot dip zinc coatings and Electroplated zinc coatings

Hot dip zinc coatings
Advantage
1. Several times thicker than electroplated zinc coatings. Hence several times as corrosion resistant and durability. Will always greatly outlast zinc electroplating in any environment.
2. The thickness of hot dip zinc coating is up to 10 times as electroplated zinc coating. The thickness depends on thickness of the part and the amount of silicon in the steel so the hot dip galvanizer is not free to pick a thickness. However, you can find out what thickness you can get on a sample part. Here is an example of the thickness: about 10 um for electrogalvanized and 55 um for hot dip.
Disadvantage
1. Doesn’t have smooth finish. May be spangled, or gray and drippy.
2. Cannot be used for bolts and nuts size M10 or smaller.

Electroplated zinc coatings (zinc plating)
Advantage
1. Smooth, shiny and drip-free. Electroplated steel is visually indistinguishable from stainless steel when new. So Electroplated zinc coatings are preferable for aesthetic reasons.
2. Significantly lower cost.
3. Doesn’t interfere with fastener threads because Zinc electroplating is thin.
4. Can be painted easily.
Disadvantage
1. Electroplating is rarely adequate for direct outdoor exposure. However, electroplating and subsequent painting is a durable combination which is used for car bodies of some premium models.
2. Less durable.

Edited by user Monday, November 29, 2010 10:17:52 PM(UTC)  | Reason: Not specified

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hong  
#2 Posted : Monday, November 29, 2010 10:22:29 PM(UTC)
hong

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PAINTING OVER HOT DIP GALVANIZED STEEL


Quote:
The painting of galvanized steel has been a difficult task for many people. The secret of good painting on galvanized steel is the surface preparation of the galvanized surface. If the surface is newly galvanized, that is less than 48 hours out of the zinc kettle, the surface can be painted after a surface roughening procedure. If the surface of the galvanized part has been exposed to the environment for more than one year then the surface can be painted after the dirt, grease and oils have been removed. The most difficult time to paint galvanized steel is between one day and one year after it has been galvanized. Following the correct surface preparation procedures can give a satisfactory duplex system.


Source: Thomas J. Langill, Ph.D., Technical Director of American Galvanizers Association

If hot dip galvanized steel becomes rusty, we can use the following process to paint it:
1. Use wire brush to clean surface;
2. Apply neutralizing materiel such as Rust Roy;
3. Apply touch-up paint.

Edited by user Monday, November 29, 2010 10:31:43 PM(UTC)  | Reason: Not specified

jane  
#3 Posted : Sunday, January 16, 2011 5:54:34 PM(UTC)
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I've had very bad experience with Chatstone Gate: they are most expensive one from our three quotes, however, my husband said the expensive one may provide the best service. However, the things have not happened in the way my husband expected. They keep telling you you need to pay additional for this item, or that to make their price even more expensive. In addition, when I asked him why you showed us about that item that was not included in your quote? He started yelling at me! What bad experience I've got!! Because the fence is once off job for most of families, they might have got away from everyone.

When we went to the workshop, the guy showed us the whole metal fence looked like. Should we get the price for what had he shown us? This is the point you need to be careful. The things he showed us had attract our attention, but were not included into his quote. So you need to pay extra for those parts that are attractive to you. Do you think this is a trap?

meiw  
#4 Posted : Monday, January 17, 2011 10:20:26 AM(UTC)
meiw

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jane wrote:
I've had very bad experience with Chatstone Gate: they are most expensive one from our three quotes, however, my husband said the expensive one may provide the best service. However, the things have not happened in the way my husband expected. They keep telling you you need to pay additional for this item, or that to make their price even more expensive. In addition, when I asked him why you showed us about that item that was not included in your quote? He started yelling at me! What bad experience I've got!! Because the fence is once off job for most of families, they might have got away from everyone.

When we went to the workshop, the guy showed us the whole metal fence looked like. Should we get the price for what had he shown us? This is the point you need to be careful. The things he showed us had attract our attention, but were not included into his quote. So you need to pay extra for those parts that are attractive to you. Do you think this is a trap?



Totally agree, Jane.

You got to remember: the more the promise they made, the more likely they will break the promise. I remember they promise us a lot, but once you paid them for the work they have done they never keep their promise.

Send me an email if anyone needs some tips on their metal fence: meiw10310@gmail.com

Edited by user Saturday, November 24, 2012 3:50:36 PM(UTC)  | Reason: Not specified

builder  
#5 Posted : Saturday, November 24, 2012 3:56:39 PM(UTC)
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meiw wrote:
jane wrote:
I've had very bad experience with Chatstone Gate: they are most expensive one from our three quotes, however, my husband said the expensive one may provide the best service. However, the things have not happened in the way my husband expected. They keep telling you you need to pay additional for this item, or that to make their price even more expensive. In addition, when I asked him why you showed us about that item that was not included in your quote? He started yelling at me! What bad experience I've got!! Because the fence is once off job for most of families, they might have got away from everyone.

When we went to the workshop, the guy showed us the whole metal fence looked like. Should we get the price for what had he shown us? This is the point you need to be careful. The things he showed us had attract our attention, but were not included into his quote. So you need to pay extra for those parts that are attractive to you. Do you think this is a trap?



Totally agree, Jane.

You got to remember: the more the promise they made, the more likely they will break the promise. I remember they promise us a lot, but once you paid them for the work they have done they never keep their promise.

Send me an email if anyone needs some tips on their metal fence: meiw10310@gmail.com


never try them, but I have heard some rumour!
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