About - Application

Application

Surface Preparation

Cleanliness

The metal substrate should first be degreased, preferably by steam-cleaning at 140 bar at 80°C. After that it should be blasted to a cleanliness degree sA 2,5 according to the standard ISO 8501-1:2007 or to the cleanliness degree as described in the standards SSPC-SP10 and NACE nr 2.

This means that the surface must be free from rust, grease, oil, paint, salt, dirt, mill scale and other contaminants. Once the blasting is completed the surface should be de-dusted with non contaminated compressed air according to the standard ISO 8502-3 (max quantity 2) or in the case of wet blasting the surface should be dried with non contaminated compressed air.

Another method to obtain a clean surface is UHP water-jetting to cleanliness degree SSPC-SP-WJ2. But keep in mind that this method does not create surface roughness.

Such a level of cleanliness is also needed when ZINGA is applied on a hot dip galvanisation or a metallisation layer, or when it is applied on top of an existing ZINGA layer, but not the same roughness degree (see further).
On small areas or on non-critical applications ZINGA can be applied on a surface that is manually prepared to degree St 2 according to ISO 8501-1.

Roughness

It is recommended to apply ZINGA on a metal substrate that has a roughness grade of medium G according to the standard ISO 8503-1:2012.

Make sure that the surface is degreased before the blasting.

Such a level of roughness is not needed when ZINGA is applied on a hotdip galvanisation or a metallisation layer, or when it is applied on top of an existing ZINGA.

Old hot-dipped surfaces have adequate roughness, new hot dipped surfaces require a sweep blast or adequate power tool roughening.

Maximum time to application

Apply the ZINGA as soon as possible on the prepared metal substrate before any contamination or corrosion occurs before coating. Otherwise the surface must be cleaned again as described above.

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Application Methods

General

Application methods

ZINGA can be applied on a clean surface by brush and roller or conventional spray-gun or by airless spraying.

Stripe coat

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

Stirring

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

Cleaning

Before and after using the spraying equipment, it must be rinsed with fresh Zingasolv. Brushes and rollers should also be rinsed with Zingasolv. Never use White spirit.

Application by Brush And Roller

Dilution

For optimal use, dilute ZINGA up to 5%, see dilution table.

First layer

The first layer must never be applied by roller, only by brush, in order to fill the cavities of the roughness profile and to wet the surface.

Type of brush or roller

Recommended industrial round brush Short hair roller (mohair)

Application by Conventional Spray-Gun

Dilution

Up to 15% with Zingasolv (see dilution table) depending on nozzle size. More dilution for same nozzle size will give a smoother surface finish.

Pressure at the nozzle

2 to 4 bar

Nozzle opening

1,8 to 2,2 mm

Special demands for spraying equipment

- For the spraying of ZINGA, it is better to remove all filters from the pistol to avoid blockage.
- The spray gun must be equipped with strong needle springs.
- Use short tubes.

Application by Airless Spraying

Dilution

Up to 7% with Zingasolv (see dilution table) depending on nozzle size. More dilution for same nozzle size will give a smoother surface finish.

Pressure at the nozzle

± 150 bar

Nozzle opening

0.017 - 0.031 inch

Zinga reloading (over hot dip) and Overcoating Zinga

Surface Preparation

General

When applying ZINGA on a Zinc surface (HDG, metallisation or ZINGA), it 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 substrate is exposed 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 ZINGA in order to obtain a perfect electrical continuity.

Additional to this, the surface has to be rough and clean to obtain maximum bond strength.

It is very important to keep the following working order in mind:

Eliminating all dirt, grease, oil and salts
Total removal of all old paint and rust
Roughening (not necessary for Zinganised surfaces)
De-dusting

Zinga Reloading

NEVER APPLY NEW ZINGA ON AN OLD ZINGANISED SURFACE THAT SHOWS FAILURE (CRACKS, DELAMINATION, PINHOLES, CRATERS, BLISTERING, ...) DUE TO BAD SURFACE PREPARATION/ APPLICATION (SALT CONTAMINATION, INADEQUATE ROUGHNESS, HEAVY BRUSH MARKS, ...). IN THIS CASE, THE ZINGA LAYER SHOULD BE COMPLETELY REMOVED.

The surface should first be cleaned to remove dirt, oils or greases by steam cleaning at 140 bar at 80°C. If steam cleaning is not an option, all surfaces must be cleaned by water-blasting at a min pressure of 150 bars.

Old weathered ZINGA has a layer of Zinc salts which form a passive barrier on ZINGA. These should be removed by one of these methods:

Sweep blasting: sweep-blasting the surface with angular non-metallic grit. This standard of blasting will remove approximately 10 to15 μm of zinc as well as all the surface contaminants. It will also provide an acceptable profile for the ZINGA to bond with. If the blast angle exceeds 45°, the blast profile will be too deep. The nozzle size must be a minimum of 10 mm. Regulate the blast-nozzle pressure at 3 bar. A test section should be done to measure the zinc thickness before and after the blast. Once the sweep- blasting is completed the surface should be de-dusted with non contaminated compressed air according to the standard ISO 8502-3 (class 2).
Sponge blasting: the pliant nature of Sponge Media abrasives allow its particles to flatten on impact, exposing the abrasive. After leaving the surface, the media expands, creating a vacuum – entrapping most of what would normally have become airborne contaminant. Up to 95% of the abrasives is recyclable.
Bristle blasting: mechanical abrasion cleaning process that is performed on metallic surfaces by a brush-like rotary power tool. A bristle blaster tool is the only power tool which can obtain proper SA 2.5 cleaning, suitable for application of ZINGA (or any high performance coating). Recommended for use of small applications and touch up.
Steel brush (less optimal - not advised).

Ensure the surfaces are completely free of surface contamination, including chloride ion levels not exceeding 50 mg/m² (when tested accordance with ISO 8502).

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

Zinga On New Hdg Or New Metallisation

The newly hot-dipped or metallised substrate should first be degreased, preferably by steam cleaning at 140 bar at 80°C or by solvent cleaning (Zingasolv).

Normally a newly metallised surface is rough enough for the application of a ZINGA layer but newly hot-dipped galvanised substrates have to be roughened (30-70 µm) in order to obtain a good adhesion.

There are different options (see ZINGA reloading):

Sweep blasting
Sponge blasting
Bristle blasting (smaller applications or touch up)
Steel brush (less optimal - not advised)

Once completed the surface should be de-dusted as described.

After the surface preparation the total surface must be completely coated with ZINGA up to the required DFT.

Zinga On Old HDG

See ZINGA on new HDG.

HP water-jetting or steam cleaning is necessary to remove dirt, grease, oil, salts, paint and rust. The rust can also be removed manually with a rotating abrasive disk or a chipping hammer (less optimal).

If the structure to be treated shows over 5% of rust, then this means that the cathodic protection of the steel is for over 50% used and local touch-ups will not be sufficient.

A surface preparation using blasting techniques is preferred. Follow the general guidelines to obtain cleanliness and roughness.

After the surface preparation the total surface must be completely coated with ZINGA up to the required DFT.

Application

The application of ZINGA on (old) hot-dipped or Zinganised surfaces is possible with brush, roller, conventional or airless spray.

It is to be noted that the first layer of ZINGA should never be applied by roller. The roller application doesn’t allow the ZINGA to penetrate sufficiently into the roughness profile of the steel.

For the same reason, the first layer of ZINGA should be diluted a little more than indicated on the Technical Data Sheet.

For brush application, it is advised to dilute the first layer of ZINGA 5 to 10% with Zingasolv to allow a brush smooth finish and a good penetration into the roughness.

Heavy brush marks (insufficient dilution and strong handling) which leave some parts of the structure too heavily coated (creation of pinholes and craters) and others not enough (unsufficient protection - spot rusting), should be avoided at all costs.

Stripe Coat

It is recommended to apply a stripe-coat of ZINGA by brush on all sharp edges, nuts and bolts and weld areas before the application of the first full layer of ZINGA to ensure that all these areas have a similar DFT to that of any adjacent surface. Please note that on new steel the sharp edges may need to be rounded off to a minimum radius of 4 mm prior to the gritblasting and the application of a stripe-coat. After the stripe-coat has dried completely, the first full coat can be applied to all surfaces.

System Recommendations

A ZINGA unique system offers good cathodic protection, is easy in application and can be reloaded. Therefore it is the preferential system for pylon protection.

In a ZINGA unique system, ZINGA is applied in two layers. The second layer is applied after a minimum drying and curing puriod of 2 hours after touch dry of the first layer. The application of the second layer should be done within a reasonable timeframe after the first layer, preventing the formation of Zinc salts between the first and second layer of ZINGA.

Therefore, if the conditions for Zinc formation are favourable (humid, warm, salty, ...), the application of the sec- ond layer should be within 24 hours of the first layer.

ZINGA is used as a stand-alone system, applied in 2 layers of 60 or 90 µm DFT. Care should be taken that the individual layer thickness are not below 80% of the specified DFT and not above 120 µm DFT for 1 layer.

Both systems are recommended for corrosive environments and tested according ISO 12944:

ZINGA 2 x 60 µm DFT

» ISO 12944-6: C4-High, C5M/I-Medium

» NORSOK M-501 syst. 7, syst. 1

ZINGA 2 x 90 µm DFT

» ISO 12944-6: C5M/I-High

With (ISO 12944):

C5I: industrial zones with high humidity and aggressive environment (continuous condensation and high pollution)
C5M: Coastal zones and marine zones with high salinity (continuous condensation and high pollution)
C4: industrial or coastal (with moderate salinity) zones (chemical factories, swimming pools, shipyards)
Medium: life expectation between 5 and 15 years
High: life expectation >15 years

It is therefore necessary to choose the system according to the environment specifications and the lifetime expectancy.