About SEAGUARD by Zinga

What is Seaguard by Zinga®?

Seaguard by Zinga layer (microscopically)

Seaguard by Zinga is a one component zinc rich coating or Film Galvanizing System containing 96% zinc (dust) in its dry film. It is s a unique form of corrosion protection because it provides both active and passive protection in a form that’s as easy to apply as a paint. The purity of the zinc used, is so high that dry Seaguard by Zinga does not contain any toxic elements. In case of mechanical damages or in case of expansion and shrinking of the metal due to temperature variations, there will be no formation of rust whatsoever.

Seaguard by Zinga offers an excellent active and passive protection:

  • The Zinc provides active, cathodic protection through galvanic sacrifice.
  • The barrier, provided by both the zinc oxides and the binder ensures a passive protection.

Seaguard by Zinga is an active zinc performance coating which works in conjunction with the metal beneath whereas paints are only passive barriers. Regardless of how thick paints are applied, they remain as barriers. Once they are breached corrosion sets in immediately. Despite this significant difference Seaguard by Zinga is still often mistaken for a paint simply because it’s liquid and comes in a tin. But there are other more subtle differences. For example it does not “skin over” in the tin because Seaguard by Zinga has an unlimited pot-life and it doesn’t go “tacky” like a paint.

Seaguard by Zinga was originally invented in Ghent University, Belgium, in the 1970’s and has since been used in a wide variety of projects throughout the world.

Comparison

Seaguard by ZingaCharacteristicsHot Dip GalvanizedPaint
Active cathodic protection
Easy application on site
Reloadable
with Seaguard by Zinga
Overcoatable
Application under extreme circumstances /
Unlimited shelf life
Contact with potable water /
Flexible layer
Welding on coated steel
Structure keeps its form during application

How does it work?

When two different metals come in contact with each other in presence of an electrolyte (e.g. water), they form a galvanic cell in which the lesser noble metal (e.g. Zn) corrodes in favour of more noble metal (e.g. steel). This electrochemical reaction is the base for the complex field that is cathodic protection.

Galvanic, cathodic protection, or active protection, arises from zinc (the anode) sacrificing itself in favour of the base metal steel (the cathode) with the resulting flow of electrons preventing steel corrosion. In this way the protection of the metal is guaranteed, even when the zinc layer is slightly damaged. Other well-established methods of cathodic protection include hot-dip galvanizing (HDG) and zinc thermal spraying both of which exhibits a constant sacrificial rate of the zinc layer.

With Seaguard by Zinga the sacrificial rate reduces dramatically after the zinc layer has oxidized and the natural porosity has been filled with zinc salts. Additionally, the zinc particles within the Seaguard by Zinga layer are protected by the organic binder without adversely affecting the electrical conductivity. This enables Seaguard by Zinga to create nearly the same galvanic potential between the zinc and the steel as hot dip galvanizing but with a lower rate of zinc loss because, put simply, the binder acts as a “corrosion inhibitor” to the zinc.

“The zinc in Seaguard by Zinga becomes the sacrificial anode in relation to the steel but it corrodes at a much slower rate than would otherwise be expected”

– Extract from B.N.F. Fulmer report of JJB Ward, Oxfordshire, Jan ’92

If the Seaguard by Zinga layer is sufficiently damaged to expose the base metal below, the steel would form a layer of surface rust but no corrosion would take place beneath it. In other words; if the surface discolouration was removed, the steel below would not be pitted or eroded. This is called “throw” or “throwing power” and enables PURE ZINC COATING to protect bare metal up to 3 – 5 mm away from where the coating ends – slightly less than new HDG. Zinc sacrificial anodes used on the steel hulls of boats below the waterline work on the same principle to protect metal in the surrounding area. Seaguard by Zinga is simply a different form of these anodes and is therefore sometimes referred to as a liquid anode or sheet anode when used in immersed conditions.

Passive Protection

The ability of zinc to provide galvanic protection is a function of its mass per given area. Dry Seaguard by Zinga contains a minimum of 96% medicinal quality zinc by weight, the particles of which are significantly smaller and purer than those found in normal “zinc rich” coatings. The Seaguard by Zinga particles’ small size and elliptical profile ensure maximum contact between both the individual particles and the substrate. This greater density of active zinc per given area combined with the good conductivity of the layer ensures that charge flows through every millimetre that has been coated and therefore provides excellent cathodic protection.

Passive Protection

Passive protection, as provided by paints and cladding, creates a “barrier” between the steel substrate and the elements. Once this barrier is compromised then the moisture and atmospheric salts will be able to start corroding the steel beneath the damaged area. This corrosion will then begin to creep extensively beneath the coating.

With Seaguard by Zinga, the organic binder and the zinc oxide layer that forms on the surface create an impervious barrier by blocking the zinc’s natural porosity with oxide particles. Unlike other passive coatings, once breached the zinc oxide layer simply renews itself by re-oxidizing. This layer of oxides is the reason behind the matt appearance of Seaguard by Zinga as opposed to the shiny hot-dipped finish.

How can it be used?

As a Stand-Alone System

Seaguard by Zinga provides comparable protection to conventional galvanizing without the need for topcoats. Although Seaguard by Zinga is only available in grey (the natural colour of zinc), the significant advantage of this form of application is that the Seaguard by Zinga layer can be re-coated at any point in the future with the bare minimum of preparation and without compromising the integrity of the coating. Seaguard by Zinga on its own is often used because the structure is already on site or too big for the molten zinc baths. Additionally, Seaguard by Zinga is commonly specified on delicate structures (wrought iron gates, sculptures) or when architectural demands require a higher standard of surface finish (no need to drill to de-gas, fettle).

For optimal protection,Seaguard by Zinga should be applied in two layers of 60 or 90 µm DFT each.

As Primer in a Duplex System

Not everybody likes the colour grey and with the additional protection of a compatible topcoat, the coating durability offered significantly increases. Seaguard by Zinga does not even have to start actively working until the topcoat has been compromised and with no underlying corrosion creep or rust bubbling, the topcoat itself inevitably lasts longer. In a duplex system (Active + Passive), Seaguard by Zinga should be applied in 1 layer of min. 60 to 80 µm DFT.

As a Shop Primer

At a thickness of 30-40 µm, Seaguard by Zinga can be used as a shop primer. The big benefit is found in the fact that the steel structures do not require reblasting before coating if Seaguard by Zinga is applied as a shop primer. The steel structure can be overcoated with Seaguard by Zinga to obtain a cathodic protection or with any other paint without the need for reblasting! Seaguard by Zinga applied steel structures can be welded and bent during assembly.

Repair for Worn and Damaged Hot-Dip Galvanized or Metal Sprayed Structures

This is probably the most common use of Seaguard by Zinga as it requires the simplest surface preparation. Seaguard by Zinga’s mechanism of protection is so similar to conventional galvanizing that they work in complete unison, as they are merely different forms of zinc. Rather than replacing galvanized assets, structures can simply have their protection “re-charged” by applying Seaguard by Zinga to the rough surface of the old galvanizing after appropriate decontamination and removal of the salts.

On Rebar

Widely used in countries where the available concrete can be of less quality, Seaguard by Zinga the steel re-bars before assembly and immersion in concrete ensures vastly increased protection from corrosion without reducing the pull-out strength of the bars. Recent tests in three independent laboratories showed that Seaguard by Zinga had at least twice the corrosion protection of either galvanized or epoxy coated rebars.

Characteristics

Easy to Apply On Site

Once thoroughly mixed, Seaguard by Zinga can be applied by using a normal paintbrush, a short-fibre roller (not for the first coat) or a conventional or airless spray-gun.

Seaguard by Zinga can be applied in a wide variety of weather conditions. The application surface temperature range is from -15°C to +40°C where conditions allow with a maximum humidity of 95% so long as the dew point is 3°C minimum above the steel temperature. Like all coatings, the substrate surface should be free from all types of contamination. Working under ambient temperatures ensures no deformation of the steel structure (which can happen in the hot-dip galvanization process) or energy loss.

Quick Drying Time

Seaguard by Zinga has one of the fastest drying times in the coating industry. It is touch dry in around 10 minutes at 20°C (40 µm DFT). Seaguard by Zinga can be recoated with a new layer of Seguard by Zinga 1 hour after touch dry (by pistol, after 2 hours by brush), and with other paints 6 to 24 hours after touch dry.This benefit allows fast system applications, and consequently shorter application times, dry dock times (for ships), less man hours and shorter close down time of structures.

Since the cost of equipment, personnel and cost through economical loss due to non-functioning of the structure is the highest of a coating project, this means Seaguard by Zinga can be an immense cost saving.

Does Not Peel Off and is Not Brittle

Our product contains so much Zinc in its dry film and it does not form a closed film. In fact, Seaguard by Zinga is porous. This is because the pigment volume concentration (for Seaguard by Zinga = the concentration of Zinc), surpasses the critical pigment volume concentration of a coating.

This means that not every zinc particle is surrounded with binder completely, allowing good contact between the zinc particles and consequently good electrical conductivity (which ensures cathodic protection).

Therefore, Seaguard by Zinga is not a paint and does not behave like a paint. When a paint is damaged, it will cause a layer of paint to ‘chip off’ or ‘peel off’. Also when damaged with a hammer, a paint will suffer from the impact which causes severe stress on the binder of the paint causing the paint to show cracks. These cracks are the weak part of the paint through which moisture and water can seep leaving the steel exposed to the environment and rusting occurs.

Seaguard by Zinga does not act like that, it acts more like the steel below: when impacted with a hammer, the Zinc is merely pushed away, bending along with the steel.

Therefore, Seaguard by Zinga can also be bent with the steel to a certain extent.

Recharging

One of the most decisive advantages of Seaguard by Zinga is that it can be recharged. Each new layer of Seaguard by Zinga makes the former layer liquid, so as to form a new homogeneous Seaguard by Zinga layer. There is no risk for accumulation of layers that are different in structure, which could cause peeling off. The surface preparation before recharging is reduced to a minimum: you only need to remove the Zinc salts of the surface. Depending on the age of the Seaguard by Zinga layer, and environmental conditions, this can be performed with a water wash, preferably by steam-cleaning at 150 bar at 80°C or by sweep blasting (very light blast).

This property of recharging can be of use if you still have to do some drilling or welding on the surface, or if the structures still have to be transported. In that case the first layer is meant as a primer. It can intercept severe damages. Afterwards the final layer of Seaguard by Zinga can be applied and local damages can be repaired. The welding seams need to be cleaned beforehand. When there is no need to recoat the whole structure, you can apply a small quantity of Seaguard by Zinga on the damaged spots and the whole structure is free from rust again. Repairs will be invisible after a certain time.

The following microscopic photos demonstrate the total integration of multiple layers of Seaguard by Zinga:

A thin film of gold dust was applied on top of the first coating of Seaguard by Zinga.

Seven days later a second coating of Seaguard by Zinga  was applied on top of the gold dust. It can be clearly seen that the gold dust has mixed completely within the two Seaguard by Zinga layers.

The same test was done with a typical “zinc-rich” paint. The gold film remains intact between the two coats demonstrating that they remain as separate layers.

Can be Top-Coated

If Seaguard by Zinga is used as part of a duplex system i.e. it is over-coated with a compatible paint system, the top-coat provides the initial barrier to the elements, but the zinc oxide will still form a secondary barrier if the outermost layer is compromised in any way. As the paint top-coat naturally begins to break down and become porous over time, the Seaguard by Zinga fills the pores from below with zinc oxides enabling the top coat to last longer. Additionally, Seaguard by Zinga does not even start to sacrifice itself until the topcoat has become damaged to the point where it is exposing the bare zinc to the elements. It is because of this that we can state that the service-life of a duplex system can be 50% more than the sum of the individual lives of Seaguard by Zinga and the paint topcoat when added together.

Always strictly adhere to the appropriate specifications provided by the topcoat manufacturers in conjunction with Seaguard by Zinga. Although Seaguard by Zinga  can be easily over-coated with a wide range of topcoats, it should be noted that when using epoxies etc. that Seaguard by Zinga is sensitive to solvents and all the necessary precautions should be taken to minimize its exposure to any solvents contained in the topcoats.

The use of the “mist-coat/full-coat” technique is vital and mandatory to prevent this from happening.  For more information, please see “mist/full coat”.

Paint manufacturers will often specify a particular individual primer/top-coat systems, and these should always be applied over the correct tie-coat. Topcoats to avoid using in conjunction with Seaguard by Zinga, include all alkyd-based enamels, which must never be applied over any zinc-based coatings. This is because the zinc reacts with the alkyd and causes saponification which allows the paint to dry but to never harden and cure.

High-build vinyls, as well as acrylated and chlorinated-rubber enamels are extremely high in solvent content, so the use of a sealer is mandatory with these coatings.

Seaguard by Zinga is a unique coating product. Before application of any topcoat, a small test application should always be performed to see if any reactions occur.

Shows Fire Retardant Properties

Seaguard by Zinga unique system shows fire retardant properties. Moreover, it does not spread flames or produce toxic flames. This has been tested by two independent laboratories.

A fire test at SGS Yarsley Technical Service (UK) found that Seaguard by Zinga  has a class 0 surface (best ranking) in flame spread ranking.

A reaction to fire test was performed at Efectis (Netherlands) in 2013. Seaguard by Zinga showed to propagation of the fire, no toxic smoke or droplets.

Can Be Welded and Applied Over Welds

Seaguard by Zinga is one of the few non-specialized coatings that can be welded and applied over welds.

The welding of steel coated with Seaguard by Zinga (max. 60 μm DFT) is possible without excessive zinc fumes because the heat of the approaching weld bead burns off the organic binder well below the melting point of zinc.

The remaining zinc dust is removed from the weld zone by convection leaving the weld-area free from contamination.

Another big advantage is the small ‘burn back’ from Seaguard by Zinga steel that is welded. In epoxy paints, this can be tens of centimeters (to meters), with Seaguard by Zinga  this burn back is limited.

Seaguard by Zinga can also be applied on welds without the needs of any special surface preparation (cleaning and roughening of the surface is necessary).

Application

Once thoroughly mixed, Seaguard by Zinga can be applied by using a normal paintbrush, a short-fiber roller (not for the first coat) or a conventional or airless spray-gun. When applying Seaguard by Zinga it must only be thinned with seaguardsolv, which is available from your nearest distributor.

Seaguard by Zinga can be applied in a wide variety of weather conditions. The application surface temperature range is from -15°C to +60°C where conditions allow with a maximum humidity of 95% so long as the steel temperature is 3°C above dew point. Like all coatings the substrate surface should be free from all types of contamination.

The broad range of allowable application conditions that Seaguard by Zinga affords means that very few days are lost during projects due to poor weather i.e. the maintenance window is extended. This, combined with Seaguard by Zinga’s unlimited shelf life, ensures minimal wastage of either time or materials during a project.

Surface Preparation

Surface preparation is the key to a good performance of any coating. Any form of contamination on the surface will create areas where the Seaguard by Zinga is not in direct contact with the steel, disrupting its electrochemical connection, the electron flow and hence the cathodic protection.

Therefore, the surface should be cleaned to be free from:

  • Dirt
  • Oils and greases
  • Salts
  • Mill scale

There are three ways to remove the contaminations from the surface:

  • Solvent cleaning
  • Detergent cleaning
  • Steam cleaning
  • Solvent cleaning is only recommended for small, non-critical applications, SeaguardSolv by Zinga can be used.

Detergent cleaning is preferred over solvent cleaning; but steam cleaning at 80°C is most preferred to create a clean surface for Seaguard by Zinga application.

Correct steel cleanliness for Seaguard by Zinga application

The second most important step in surface preparation is the creation of a surface profile. This ensures adhesion of the coating to the substrate. Seaguard by Zinga will only adhere adequately on a rough surface!

A surface profile consists of profile depth and profile roughness. For good Seaguard by Zinga adhesion, Seaguard Film Galvanizing System advises a profile depth between Rz 50 and 70 µm and a profile roughness Ra 12.5.

To create this roughness, the substrate should be grit blasted or slurry blasted to SA 2.5 (cleanliness) – or by using a steel brush for small, non-critical applications. If the surface already has adequate roughness (due to weathering or previous blasting), the surface can also be cleaned to SA 2.5 by using UHP washing.

Always keep in mind: the performance of Seaguard by Zinga depends highly on the quality of the surface preparation!

Application Methods

Once thoroughly mixed, Seaguard by Zinga can be applied by using a normal  paintbrush,a short-fiber roller(not for the first coat) or a conventional or airless spray-gun.

Seaguard by Zinga must be thoroughly mechanically stirred to achieve a homogeneous liquid before application. After a maximum of 20 minutes, re-mixing is necessary.

Application by Brush or Roller

Seaguard by Zinga can be applied using a normal paintbrush (natural hairs) or a short-fiber roller for smaller applications or to perform a stripe-coat.

In order to fill the profile of the substrate better, it is advised to dilute Seaguard by Zinga 3-5% (mass on mass – see below dilution table). This will give a smoother finish.

It is always recommended to treat corners, sharp edges, bolts and nuts with a stripe coat (by brush) before applying a uniform coat by spray.

For more technical data, see Technical Data Sheet of Seaguard by Zinga.

Application by Conventional Spray

Seaguard by Zinga can be applied using a conventional spray gun. In order to ensure good circulation of the Seaguard by Zinga, it should be diluted 10 to 20% (mass on mass – see below dilution table) depending on pressure at the nozzle and nozzle opening. More dilution for the same nozzle will give a smoother surface finish (less porous).

For more technical data, see Technical Data Sheet of Seaguard by Zinga.

Application by Airless Spray

Seaguard by Zinga can be applied using a conventional spray gun. In order to ensure good circulation of the Seaguard by Zinga, it should be diluted 5 to 7% (mass on mass – see below dilution table) depending on pressure at the nozzle and nozzle opening. More dilution for the same nozzle will give a smoother surface finish (less porous).

For more technical data, see Technical Data Sheet of Seaguard by Zinga.

Dilution Table

 Brush or Roller
3-5%
Conventional Spray
10-20%
Airless Spray
5-7%
1 kg0.03-0.05 kg /
0.034-0.057 L MULTI METAL SOLVENT
0.10-0.20 kg /
0.114-0.228 L MULTI METAL SOLVENT
0.05-0.07 kg /
0.057-0.080 L MULTI METAL SOLVENT
2 kg0.06-0.10 kg /
0.068-0.114 L MULTI METAL SOLVENT
0.20-0.40 kg /
0.228-0.457 L MULTI METAL SOLVENT
0.10-0.14 kg /
0.114-0.160 L MULTI METAL SOLVENT
5 kg0.15-0.25 kg /
0.171-0.285 L MULTI METAL SOLVENT
0.50-1.00 kg /
0.571-1.142 L MULTI METAL SOLVENT
0.25-0.35 kg /
0.285-0.400 L MULTI METAL SOLVENT
10 kg0.30-0.50 kg /
0.342-0.571 L MULTI METAL SOLVENT
1.00-2.00 kg /
1.142-2.283 L MULTI METAL SOLVENT
0.50-0.70 kg /
0.571-0.800 L MULTI METAL SOLVENT
25 kg0.75-1.25 kg /
0.856-1.427 L MULTI METAL SOLVENT
2.50-5.00 kg /
2.854-5.708 L MULTI METAL SOLVENT
1.25-1.75 kg /
1.427-1.998 L MULTI METAL SOLVENT

Seaguard by Zinga on Old Hot Dip

When applying Seaguard by Zinga on a Zinc surface,Seaguard by Zinga has to come in contact with pure metallic Zinc to ensure a good electrochemical connection and hence a cathodic protection of the substrate.

If a Zinc rich substrate is subjected to the environment, it will form Zinc salts (zinc oxides, zinc carbonates and others) which form a barrier.

This zinc salt barrier has to be removed before applying Seaguard by Zinga.

For more information, please contact the Seaguard Film Galvanizing System Technical Team.

Seaguard by Zinga Reloading

The surface should first be cleaned to remove dirt, oils or greases by steam cleaning at 140 bar at 80°C (preferably) or solvent cleaning (SeaguardSolv by Zinga).

Old weathered Seaguard by Zinga has a layer of Zinc salts which form a passive barrier on Seaguard by Zinga. This zinc salt barrier has to be removed before applying Seaguard by Zinga.

To test if all Zinc salts are removed: rub a clean test area with a clean, white, lint free cloth dipped in SeaguardSolv by Zinga. If the white cloth shows a dark grey colour, the surface is ready to coat. If the cloth remains white or light grey, the surface must be given more preparation by the chosen option.

For more information, please contact the Seaguard Film Galvanizing System Technical Team.

Overcoating Seaguard by Zinga

Seaguard by Zinga can be overcoated with a topcoat to give a coloured finish to the structures.

Like all porous Zinc rich coatings, care should be taken to ensure compatibility of the topcoat with Seaguard by Zinga.

In practical conditions, we advise the use of a sealer to avoid any problems with the compatibility of the topcoat.

It is not possible to give an extensive list of products which are or are not compatible with Seaguard by Zinga. Every topcoat has its specific characteristics which make compatibility on Seaguard by Zinga more or less likely.

We can only give general guidelines to detect whether or not it is likely that a topcoat is suitable for use on Seaguard by Zinga or not.

General Guidelines

Listed characteristics below can give a good indication on the compatibility for Seaguard by Zinga.

1. Paint type.

Never apply alkyd paints on Seaguard by Zinga. The alkyd will react with the Zinc and make it saponify.

Water based products can cause formation of Zinc salts underneath the topcoat, resulting in bad adhesion. Water based coatings should not be used on top of Seaguard by Zinga.

2. Drying time.

In general,fast drying paints perform a lot better on Seaguard by Zinga. Fast drying paints allow less time for the solvent of the topcoat to penetrate the Seaguard by Zinga layer and consequently damage its cathodic capacities. Ideally, the paint should not have a touch dry time (20°C) of more than 1 hour, with 2-3 hours maximum.

3. Acid formation.

If the topcoat forms acid products upon curing, this can affect the Seaguard by Zinga coating. Information on the product formation upon curing can be found in MSDS sheets.

4. Time for complete cure / polymerization.

If a paint is fully cured, it can no longer affect the Seaguard by Zinga layer. If this cure time is short, the impact on Seaguard by Zinga is also reduced, insuring better compatibility.

5. Sulphates in binder and/or solvent.

Seaguard by Zinga is sensitive to sulphates. Therefore topcoats containing sulphates should be avoided.

Testing Compatibility

If a topcoat is used directly onto Seaguard by Zinga, it is advised to always perform a small test application on a test plate. This prevents problems on a big structure and also gives the applicator the chance to get to know the product.

For more information, please contact the Seaguard Film Galvanizing System Technical Team.

Mist/Full Coat Technique

To avoid bubbling of a topcoat or sealer overSeaguard by Zinga, we advise to apply the paints using a mist/full coat technique.

A thin coat of sealer or topcoat is applied over the surface of Seaguard by Zinga before a full pass of the coating at the normal film thickness. This thin film penetrates only the surface layers of the Seaguard by Zinga and seals its surface. Also relatively porous, the mist coat presents little obstacle to the passage of air from these upper layers.

Mist Coat
Application at least 6 hours after Seaguard by Zinga is touch-dry.
25 to 30 μm DFT >continuous layer.
Normal dilution according to the technical data sheet.
Full Coat
Application at least 2 hours after the mist coat is touch-dry.
Specified layer thickness minus 25 to 30 μm DFT (of mist coat).
Normal dilution according to the technical data sheet.

First, a thin continuous layer is applied which gives air bubbles easy passage through the film. The first mist coat also provides a barrier for aggressive solvents in the topcoat.

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