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FAQs

Please find information below and frequently asked questions related to both galvanizing and powder coating.

Galvanizing FAQs

What is the size of your galvanizing bath?

Maximum Material Dimension
Length Width Height
7.2m long 1.7m wide 2.75m high
*Max weight lift - 5 tonne.
Contact sales team for any technical queries.

How long does it take to galvanize steel?

Galvanizing lead times vary depending on the volume, size and type of material. Generally the process of galvanizing takes approximately half a day, though consideration must be taken on the time of year and how much demand there is within the industry. Contact us at the early stage in the planning process so that we can advise you on suitable methods of design and fabrication. Many delays are caused by inappropriate design and a lack of understanding of the galvanize process.

Is there an express service?

For those fast - jobs that just cant wait, the 'NK Express Service' offers a 24 hour turn around and is available on request.

What life span can I expect from galvanized material?

The galvanizers association has advised that a standard galvanized coating may now achieve a coating life of 50 years in most environments, although urban / marine are up to 25 years.

Why is some galvanized material shiny and some dull?

Dark grey or light grey - its all galvanized.

Protection is equal - and often better - with dark grey coatings than with light grey coatings.

When rimmed or aluminium killed steels are hot dip galvanized, compact zinc-iron alloy layers are formed and covered by zinc, which has a light bluish grey lustre. In some cases the zinc can form randomly oriented crystals to give a 'spangle' finish but this is not a sign of either good or poor hot tip galvanizing, nor does spangle affect the corrosion resistance of the zinc coating. Silicon, which is sometimes added to steel as a deoxidant during its production, speeds up the reaction between the steel and molten zinc. When the steel part is removed from the galvanizing bath but still remains hot, the reaction may continue and convert all or part of the surface zinc layers to zinc-iron alloys.

Zinc iron alloys are dark-grey compared with the light grey of zinc and are more abrasion resistant.

Usually zinc-iron alloy coatings form more thickly and hence give longer life than the coatings on rimmed or aluminium killed steels. The zinc-iron alloys in any case have at least as good corrosion resistance as zinc, thickness for thickness can have better intrinsic corrosion resistance in acid industrial environments. These thick coatings can be more susceptible to mechanical damage particularly if handled roughly, and appropriate care must be taken.

The dark grey coating surface may develop iron oxide staining on atmosphere exposure, even in mild conditions when moist. This is only a surface effect and does not develop into nodular or flaking rust: the galvanized coating remains intact to protect the steel.

I have material that has been galvanized, its appears to look rusty, why?

Sound galvanized steel with many years of corrosion-free life ahead can sometimes be rust stained or discoloured. This may give an incorrect impression that the coating has failed and is, in some cases, visually unacceptable. Below illustrates the main causes of staining and discolouration and indicates how the problems can be avoided or the effects remedied. The staining and discolouration of galvanized coatings by rust may occur as a result of one or more factors:

1. Direct contact of galvanized parts with unprotected or inadequately steel (e.g. galvanized steel sections fastened with unprotected, electroplated or painted steel bolts).
2. Deposits of iron dust and swarf from other operations or sources onto the galvanized surface.
3. Water draining from unprotected or poorly protected steelwork, e.g. from damaged areas on painted steelwork.
4. During pickling, hydrochloric acid may penetrate into the weld area via pin holes or if the welding is intermittent. Residual salts can sometimes pick up water and cause 'weeping' from the weld areas. This effect is normally limited to a small area, ceases after a short time and is not detrimental to the coating.
5. Rusting of areas welded after galvanizing and subsequently left unprotected or inadequately protected.
6. Staining of galvanizing can occur when water runs off other materials notably metals such as copper, certain hardwoods, e.g. oak, an indeed whenever water can dissolve materials from one surface and redeposit on the galvanized steel.

How can I avoid this?

All parts of the structure should receive comparable corrosion protection where possible. The thinner zinc coatings frequently supplied on steel mesh, sheet, wire and tube will not last as long as those of products hot dip galvanized to BE/IS EN 1SO 1461, the standard which covers all structures galvanized after fabrication.

Welds should be continuous and slag-free wherever possible to minimise the retention of pickle residues.

Design structures to avoid run -off water from other metals on to galvanized steel. In particular avoid run-off from inadequately protected steel and from copper.

Where welding after galvanizing is necessary, welded areas should be thoroughly cleaned and the zinc coating restored either with an appropriate thickness of zinc rich paint or with a proprietary repair compound, in accordance with section 6.3 of BS/IS EN ISO 1461.

What is Remedial Treatment

Discolouration and staining have no effect on the life of the coating. However, affected areas may be cleaned to improve the appearance of the structure. Generally, wire brushing or the use of a scouring powder will remove the stain and leave a sound galvanized coating.

How do you repair damaged areas?

Small areas of galvanizing may be damaged by operations such as cutting or welding after galvanizing. Because of the sacrificial action of zinc, small localised flaws (typically up to 5mm diameter) tend to be self-healing and have little effect on the life of the coating. Nevertheless, it is often aesthetically desirable to renew the coating over small areas as well as larger areas using one of the following techniques:

a) Thoroughly wire brush the affected areas and apply several coats of zinc rich paint to give a coating thickness at least equivalent to the original galvanizing.

b) Thoroughly wire brush, heat the bare area with a blow torch to 300C and apply a special zinc alloy rod.

Painting with zinc rich paint is usually simplest but if a colour match is important, the zinc alloy rods are usually most suitable.

Contact the sales team for technical queries.

Powder Coating FAQs

How long does it take to powder coat material?

Powder coating lead times vary depending on the volume /size / type of material. Generally the process of powder coating takes approximately half a day, though consideration must be taken on the time of year and how much demand there is within the industry.

Contact us at the early stage in the planning process so that we can advise you on suitable methods of design and fabrication. Many delays are caused by inappropriate design and a lack of understanding of the powder coating process.

Is there an express service

For those fast - tract jobs that just cant wait, the 'NK Express Service' offers a 24 hour turnaround on request.

Contact our sales team for more information

Why should I powder coat material instead of wet paint?

As one of the fastest growing finishing technologies in the world, powder coating is also extremely cost - effective when set against labour intensive traditional liquid coatings.

This modern surface coating system is a high quality finish application that is extremely decorative and more resistant to chemicals, chipping, peeling and wearing than other finishes.

The quality systems in our powder coating division have enabled us to obtain Qualicoat Approvalship - the highest European standard in powder application.

We are an approved applicator of Akzo Nobel - interpon d and Dupont powder - a proven powder finish system that has been tried and tested throughout the industry for over 10 years.

We can pass on our confidence in the outstanding quality of product and service through our unique extended guarantees. Contact our sales team for further information.

Generally powder coating life expectancy is approximately 25 - 15 years, depending on the material. Though in areas where the coating may come in contact with concentrated atmospheric pollutants [marine, chemical], the life expectancy would be shorter due to the environment. Please contact the sales team for technical information.

What colours can I powder coat?

Almost every design palette is catered for with a wide range of colours, finishes and textures and the system can be applied to a variety of surface finishes and fabrications. You can view a list of available colours on our Colour Chart, via the download page of this site.

Can you repair damaged areas?

Yes, this is possible. Please contact our sales technical sales team who will be able to specify the procedures required for your material.

Cleaning and Maintenance of powder coating.

NK Coatings Limited powder application is recognised as being in the forefront foe quality and finish. However, in order to preserve the aesthetic finish it is recommended to regularly clean the coating.

Regular cleaning, on a maximum 3 month interval or to a mutually agreed timescale, using warm water and mild detergent. Abrasive cleaners including strong solvent must not be used to remove any heavy soiling. Where spirit should only be considered if the mild detergent is not strong enough.

In areas where the coating may come in contact with concentrated atmospheric pollutants [marine, chemical] it would be prudent to clean more frequently, E.G monthly.

Full documentation of the cleaning schedule must be maintained.

If damage occurs to the coating, repairs must be carried out immediately, contact N.K. Coatings Limited.

What size can you powder coat?

Maximum working envelope
Length Width Height
6.8m long 0.850 wide 2.8 high


Maximum dimensions
Length Width Height
6.6m long 0.800m wide 2.7m high

What colours can you offer?

You can view colour charts via the links below:

NK Coatings is the the market-leader in metal finishing services in Ireland, based in Mallusk.