Hempel Sealer Epoxy Sealant - 750ml

Hempel’s Sealer 05991 is a transparent, low-viscosity, two-component epoxy sealer for porous wood and plywood, and for saturating exposed glass-fibre laminate after gelcoat removal during osmosis repair. Suitable for interior and exterior use above or below the waterline, it mixes 4:1 by volume and has a theoretical spreading rate of 10m²/L at a 30µm dry film thickness.

Hempel’s Sealer is designed to penetrate and seal absorbent marine substrates rather than leave a heavy surface film. The product is supplied as Base 05999 and Curing Agent 95040, producing a transparent, flat finish after mixing. It has 29 ± 2% volume solids and a specific gravity of 0.9kg/L.

The current Hempel Yacht range lists a 750ml pack. At the stated theoretical spreading rate, one 750ml pack covers approximately 7.5m² at the reference 30µm dry film thickness under theoretical conditions. Actual coverage depends on substrate porosity, surface profile and application losses.

Intended Applications and Compatibility

Use Hempel’s Sealer on dry, absorbent wood and plywood. For glass fibre, Hempel specifies saturation of the laminate after loose or defective gelcoat has been removed and absorbed moisture has evaporated, as part of an osmosis-repair coating system. The current Product Data Sheet does not list intact gelcoat as a general application surface.

The product is suitable for interior and exterior marine areas above and below the waterline. Recommended subsequent coatings are Hempel’s Light Primer 45551, Hempel’s Underwater Primer 26030 and Hempel’s varnishes, including Hempel’s Classic Varnish.

Surface Preparation

Remove oil, grease and other contaminants with a suitable detergent. Wood and plywood must be completely dry, with a moisture content below 16%, and must be capable of absorbing the sealer completely. Do not pre-treat the wood with ordinary priming oils or commercial anti-mould fluids.

For glass-fibre laminate, remove all loose or defective gelcoat and allow absorbed moisture to evaporate before application. Previously coated surfaces must be abraded, cleaned and dried.

Mixing and Application

Stir Base 05999, add Curing Agent 95040 and mix thoroughly in a 4:1 ratio by volume. Allow the mixed product to stand for several minutes so trapped air bubbles can escape. Do not dilute the two components separately.

Brush application is recommended because it allows the sealer to be worked into the substrate. Apply only enough product to saturate and seal the surface. The finished surface must not remain glossy; remove any surplus surface layer before applying the next coat.

Use Hempel’s Thinner 845 (No. 5), product code 08451, for thinning and tool cleaning. Add thinner only where required and limit thinning to a maximum of 5% of the mixed product. The stated pot life is 16 hours at a product temperature of 10°C.

Keep the surface temperature above 10°C during application and curing. Relative humidity must remain below 85% during drying and curing. Maintain sufficient ventilation and prevent condensation on the freshly applied coating.

Drying and Overcoating

At the reference 30µm dry film thickness, Hempel’s Sealer is touch dry in approximately four hours at 20°C or eight hours at 10°C. It is ready to sand after approximately 24 hours at 20°C and fully cured after seven days at 20°C or 14 days at 10°C.

At 20°C, the minimum overcoating interval is four hours for Hempel’s Light Primer 45551, Hempel’s Underwater Primer 26030 and Hempel’s Classic Varnish. At 10°C, the minimum interval is 10 hours. Hempel states no maximum interval for these coatings, but the surface must be clean before overcoating. When applying a single-component product over this two-component sealer, Hempel advises overcoating while the surface is almost dry but still slightly tacky.

Key Features

• Official Hempel product code 05991
• Transparent two-component epoxy sealer
• Low-viscosity formulation with good penetration properties
• Designed for porous marine substrates
• Suitable for wood and plywood
• Suitable for exposed glass-fibre laminate after gelcoat removal
• Specified for saturation during osmosis-repair work
• For interior and exterior use
• Suitable above and below the waterline
• Base 05999 and Curing Agent 95040
• Mixing ratio: 4:1 by volume
• Standard shade: Transparent 00000
• Flat finish
• Volume solids: 29 ± 2%
• Specific gravity: 0.9kg/L
• Reference dry film thickness: 30µm
• Reference wet film thickness: 105µm
• Theoretical spreading rate: 10m²/L
• Approximate theoretical coverage per 750ml pack: 7.5m²
• Brush application recommended
• Maximum thinning: 5% of the mixed product
• Thinner and cleaner: Hempel’s Thinner 845 (No. 5), 08451
• Pot life: 16 hours at a product temperature of 10°C
• Touch dry in approximately four hours at 20°C
• Ready to sand in approximately 24 hours at 20°C
• Fully cured in approximately seven days at 20°C
• Recommended subsequent coats include Hempel’s Light Primer, Underwater Primer and varnishes
• Flash point: 26°C
• EU VOC content of mixed product: 606g/L
• Base and curing-agent shelf life: 36 months at 25°C in original unopened containers
• Current listed UK pack size: 750ml

Frequently Asked Questions

What is Hempel’s Sealer 05991 used for?
It is used to penetrate and seal porous wood and plywood, and to saturate exposed glass-fibre laminate after gelcoat removal during osmosis-repair work.

Can Hempel’s Sealer be used above and below the waterline?
Yes. Hempel specifies it for interior and exterior use both above and below the waterline.

Can it be applied over intact gelcoat?
The current Hempel Product Data Sheet specifies glass-fibre use after loose or defective gelcoat has been removed and absorbed moisture has evaporated. It does not list intact gelcoat as a general application surface.

Does Hempel’s Sealer repair osmosis by itself?
No. It is used to saturate exposed glass-fibre laminate after gelcoat removal as one stage of an osmosis-repair coating system. The remaining repair and coating stages must follow the applicable Hempel specification.

How dry must wood be before application?
Wood and plywood must be completely dry, with a moisture content below 16%, and capable of absorbing the sealer fully.

Can ordinary wood primer or anti-mould treatment be applied first?
No. Hempel states that wood must not be primed with ordinary priming oils or commercial anti-mould fluids before the sealer is applied.

What is the mixing ratio?
Mix Base 05999 and Curing Agent 95040 in a 4:1 ratio by volume. Stir the base first, add the curing agent, mix thoroughly and allow the mixture to rest for several minutes so air bubbles can escape.

What is the pot life?
The current Product Data Sheet states a pot life of 16 hours at a product temperature of 10°C. It does not provide a separate pot-life figure at 20°C.

How should Hempel’s Sealer be applied?
Brush application is recommended so the low-viscosity sealer can be worked into the substrate. Apply only enough to saturate the surface.

Should the sealed surface look glossy?
No. Hempel states that the surface must not appear glossy after application. Remove any surplus top layer before applying the subsequent coat.

Which thinner should be used?
Use Hempel’s Thinner 845 (No. 5), product code 08451, as both thinner and tool cleaner. Thin the mixed product only, never the separate components, and do not exceed 5%.

How much area does one litre cover?
The theoretical spreading rate is 10m²/L at a 30µm dry film thickness. A 750ml pack therefore covers approximately 7.5m² theoretically. Practical coverage will be lower on highly porous or uneven substrates.

How long does Hempel’s Sealer take to dry?
It is touch dry after approximately four hours at 20°C or eight hours at 10°C. At 20°C, it is ready to sand after about 24 hours and fully cured after seven days.

Which coatings can be applied over Hempel’s Sealer?
Hempel lists Hempel’s Light Primer 45551, Hempel’s Underwater Primer 26030 and Hempel’s varnishes as recommended subsequent coatings.

When can it be overcoated?
At 20°C, the stated minimum interval is four hours. At 10°C, it is 10 hours. Hempel states no maximum interval for the listed subsequent coatings, provided the surface remains clean and correctly prepared.

What application conditions are required?
The surface temperature must remain above 10°C during application and curing. Relative humidity must remain below 85%, adequate ventilation must be maintained and condensation must be avoided.

How should the product be stored?
Store both components in original, tightly closed containers in a dry, shaded, cool and well-ventilated area away from heat and ignition sources. The curing agent is moisture-sensitive. The stated shelf life is 36 months at 25°C.