Hempel Pro Blacking Finishing Coat - 5 Litre

Hempel’s Pro Blacking 46500 is a fast-drying, physically drying, self-priming underwater hull coating for narrowboats, inland watercraft and similar vessels. It is resistant to salt and fresh water, provides good anticorrosive protection and has a theoretical spreading rate of 5.2m²/L at the recommended 80µm dry film thickness.

Designed for newbuild, maintenance and repair work, Hempel’s Pro Blacking combines primer and finishing-coat functions in one physically drying coating. It dries to a flat black finish in standard shade Black 19990 and may be used throughout the year, provided the specified surface and application conditions are met.

The coating has 41 ± 2% volume solids, a specific gravity of 1.3kg/L and a maximum dry-exposure service temperature of 80°C. Hempel classifies the product for professional use only.

Intended Applications and Compatibility

Hempel recommends Pro Blacking as a self-priming finishing coat for underwater hulls, particularly on narrowboats, inland watercraft and similar vessels. The Product Data Sheet provides preparation standards for steel surfaces. It does not state compatibility with glass fibre, aluminium or timber, so use on those substrates should be confirmed with Hempel before application.

The Product Data Sheet describes Pro Blacking as an anticorrosive underwater finishing coat and does not claim biocidal antifouling performance. Where fouling control is required, use a coating system specified by Hempel for that purpose.

Surface Preparation

Remove oil, grease and other contaminants using a suitable detergent. Remove dust, spent blast media and loose material before coating.

For newbuild steel, abrasive blast to a minimum of Sa 2½ in accordance with ISO 8501-1 or SP 10 in accordance with SSPC. Damage to shopprimer and contamination caused by storage or fabrication must be thoroughly removed by suitable mechanical or chemical cleaning before final painting.

For maintenance and repair, abrasive blast to a minimum of Sa 2 in accordance with ISO 8501-1 or SP 6 in accordance with SSPC. Minor areas may be prepared using hand or power tools instead of abrasive blasting. Remove all residual dust and loose material before application.

Application

Hempel’s Thinner 08080 is specified for thinning and equipment cleaning. For airless spray, the maximum stated thinning is 5% by volume. Indicative spray settings are 150 bar nozzle pressure and a 0.021–0.023-inch nozzle orifice at a material temperature of 20°C. Spray data are indicative and must be adjusted to suit application conditions and equipment.

Brush or roller application is permitted, but additional coats will be required to achieve the specified dry film thickness. Hempel does not state a brush or roller thinning percentage in the Product Data Sheet. Avoid excessive film thickness.

The recommended film build is 80µm dry film thickness and 190µm wet film thickness, giving a theoretical spreading rate of 5.2m²/L. The stated specification range is 40–100µm dry film thickness, corresponding to 100–250µm wet film thickness and a theoretical spreading range of 10–4.1m²/L.

Apply only to a clean, dry surface at least 3°C above the dew point. Maintain adequate ventilation during application and drying.

Drying and Overcoating

At 20°C and the recommended 80µm dry film thickness, Hempel’s Pro Blacking is touch dry in approximately 60 minutes. This is a touch-dry time only and should not be treated as a relaunch or immersion time.

The Product Data Sheet does not provide a fixed overcoating or relaunch interval. Previous and subsequent coats are listed as none or according to Hempel’s specification. The surface must be dry and clean before further application, and sufficient ventilation must be maintained during application, drying and curing.

Key Features

• Hempel product code 46500
• Fast-drying, physically drying underwater coating
• Self-priming finishing coat
• Suitable for narrowboats, inland watercraft and similar vessels
• For underwater hull applications
• Resistant to salt and fresh water
• Good anticorrosive properties
• Suitable for newbuild, maintenance and repair work
• All-year-round application, subject to specified conditions
• Standard shade Black 19990
• Flat finish
• Volume solids: 41 ± 2%
• Specific gravity: 1.3kg/L
• Recommended dry film thickness: 80µm
• Recommended wet film thickness: 190µm
• Theoretical spreading rate: 5.2m²/L at the recommended film thickness
• Apply by airless spray, brush or roller
• Airless spray thinning: maximum 5% by volume
• Specified thinner and cleaner: Hempel’s Thinner 08080
• Touch dry in approximately 60 minutes at 20°C
• Maximum dry-exposure service temperature: 80°C
• Flash point: 32°C
• EU VOC content: 512g/L; value may vary by shade
• Shelf life: 60 months at 25°C in original unopened containers
• Professional use only
  

Frequently Asked Questions

What is Hempel’s Pro Blacking 46500 used for?
It is a self-priming finishing coat for underwater hulls, particularly on narrowboats, inland watercraft and similar vessels. It is suitable for newbuild, maintenance and repair work.

Is Hempel Pro Blacking self-priming?
Yes. Hempel describes it as a self-priming finishing coat. Self-priming does not remove the need for the specified cleaning and steel-preparation standard.

Can it be used in salt water and fresh water?
Yes. Hempel states that the coating is resistant to both salt and fresh water.

Is Hempel Pro Blacking an antifouling paint?
The Product Data Sheet describes it as an anticorrosive underwater finishing coat and does not claim biocidal antifouling performance. Use a Hempel-specified fouling-control system where antifouling protection is required.

Which substrates are suitable?
The Product Data Sheet provides preparation standards for steel surfaces. It does not confirm use on glass fibre, aluminium or timber, so those substrates should be checked with Hempel before application.

How should new steel be prepared?
Abrasive blast to at least Sa 2½ under ISO 8501-1 or SP 10 under SSPC. Thoroughly remove damaged shopprimer, fabrication contamination, dust, blast media and loose material.

How should an existing steel hull be prepared for maintenance?
Abrasive blast to at least Sa 2 under ISO 8501-1 or SP 6 under SSPC. Minor areas may be hand or power tool cleaned. The final surface must be clean, dry and free from oil, grease, dust and loose material.

How can Hempel Pro Blacking be applied?
It can be applied by airless spray, brush or roller. Brush and roller application will require additional coats to reach the specified dry film thickness.

Which thinner should be used?
Use Hempel’s Thinner 08080 for thinning and equipment cleaning.

What are the airless-spray settings?
The indicative settings are 150 bar nozzle pressure, a 0.021–0.023-inch nozzle orifice and no more than 5% thinning by volume. These figures are based on material at 20°C and may require adjustment.

How much area does one litre cover?
The theoretical spreading rate is 5.2m²/L at the recommended 80µm dry film thickness. Depending on the selected film thickness, the stated theoretical range is 10–4.1m²/L. Practical coverage will be lower where surface profile and application losses increase consumption.

How long does Hempel Pro Blacking take to dry?
It is touch dry in approximately 60 minutes at 20°C when applied at the recommended 80µm dry film thickness. Lower temperatures, greater film build and restricted ventilation can extend drying.

When can the hull be overcoated or relaunched?
The Product Data Sheet does not provide a fixed overcoating or immersion interval. Follow the Hempel specification for the project and do not use the 60-minute touch-dry time as a relaunch time.

Can it be applied throughout the year?
Hempel describes the product as suitable for all-year-round use. The surface must still be clean and dry, at least 3°C above the dew point, with adequate ventilation during application and drying.

How should the product be stored?
Store it in accordance with the product label, Safety Data Sheet and local regulations, protected from direct sunlight, rain and snow. The stated shelf life is 60 months at 25°C in the original unopened container; elevated storage temperatures may reduce shelf life.

Is Hempel Pro Blacking intended for professional use?
Yes. The Product Data Sheet states that it is for professional use only. Always consult the Product Data Sheet and Safety Data Sheet supplied with the product before application.