Aithon PV33

Approved Contractor

Aithon PV33 Timber Fire Protection

AITHON PV33 is a superior waterborne intumescent varnish that provides fire protection to the timber. It’s recommended for various interior fire protection of timber and is easy to use and quick drying.

In the event of a fire, the product coating swells forming a micro-cellular foam layer more than 3cm thick and is resistant to more than 1000°c.

This acts as an insulating barrier between the flame and the timber allowing more time before hazards worsen.

The unique gel properties in the Aithon PV33 basecoat and the advanced Aithon F3 finish coat, provide an unrivalled decorative and protected finish. 

  • Up to 60 minutes fire resistance on timber beams and columns
  • R15, R30, R45 and R60 Fire resistance (EN 13381-7 and EN 13501-2)
  • Reduces the speed of carbonization up to 0,33 mm/min (unprotected timber: 0,8 mm/min according to Eurocode 5 – Timber Structures)
  • Class B-s1-d0 (EN 13501-1 and EN 13501-2)
  • ETA 15/0424
  • Class A (ASTM E84)
  • Perfectly transparent
  • Easy application by brush, roller or spray
  • High transparency, with matt wax finish coat
Glulan Timber Fire Protection
Timber Fire Protection
Timber Fire Resistance

Up to 60 minutes fire resistance

Using AITHON PV33 it is possible to upgrade the fire resistance class of historical buildings and at the same time, protect their ancient beauty saving the original timber frame.

Also, reducing the environmental impact of the restoration works.

In new buildings, fire resistance is achieved by oversizing the timber beams and columns to compensate for the wood thickness which is carbonized in a fire situation.

Reducing the carbonization speed, AITHON PV33 allows designers to reduce timber oversizing, thus saving the cost and weight of the timber frame.

Applying Aithon PV33

How It Works

  • Check the ambient temperature and humidity to ensure that they are within the recommended limits throughout the application time.
  • Check timber humidity.
  • Ensure that the timber surface is free from dust, wax, oil, or other water-repellent products which may affect AITHON PV33 adhesion. In case of doubt, we recommend the preparation of test specimens, with and without a certain degree of surface preparation, in order to choose the most appropriate procedure.
  • Stir thoroughly before use.
  • Ensure appropriate PPE is available (gloves, goggles and face mask) in accordance with the health and safety data sheet.

Substrate Preperation

AITHON PV33 is water-borne and its adhesion is related to the natural porosity of the timber.

If the timber has already been treated with a varnish, with oil or wax products and the timber porosity has been reduced, the adhesion of AITHON PV33 can be significantly affected.

It is often very difficult to eliminate completely the existing products from the timber surface.

A proper sandblasting is often not possible due to ambient restrictions; at least the entire surface needs to be carefully cleaned using a 150 or 180-grade sandpaper if timber is already treated.

Otherwise, the adhesion in the long term may be affected, even if it seemed satisfactory at the time of application.

If you have any doubt regarding the compatibility of AITHON PV33 with your timber substrate, please advise our Technical Service.

Site Requirements

Aithon PV33 should not be applied where ambient humidity exceeds 70%.

It is important not to exceed the ambient humidity as this will affect the drying of the product and it will remain sticky.

If Aithon F3 top seal is applied onto a non cured product then this can cause long term durability problems and may result in local delamination.

Apply AITHON PV33 when the ambient temperature is between 5°C and 30°C; it is important that the temperature remains above 5°C throughout the drying process.

The timber humidity at the time of application should be below 12%.

A higher timber humidity does not affect AITHON PV33 adhesion but the varnish drying process will slow down and the film may remain sticky until timber excess of humidity has been released to the ambient air.

In this case, we recommend to heat the site and provide suitable ventilation to help both timber and the varnish to dry.


AITHON PV33 can be applied by brush, roller or a spray gun.

For spray application, the best results are achieved using double-orifice nozzles, like the T93R manufactured by Tritech Industries Inc. Stir thoroughly before use.

For application at low temperature (5°C – 10°C), it may be convenient to heat AITHON PV33 up to 40 – 50°C.

For airless spray application at low temperature, an electric heating unit can be inserted between the pump and the gun.

Please contact your airless pump supplier for more information on these heating units.

The required quantity of AITHON PV33 for fire classification is the following:


AITHON PV33 is supplied as a gel product.

It can be spray applied as it is or thinned with 5% water. Brush or roller application requires a 10% to 20% thinning with water.

AITHON F3 may be used as it is or thinned with white spirit. Usually, 10% of thinning is sufficient.


AITHON PV33 (basecoat): 300 gr/m2 can be applied in one or two coats.

Applying one coat per day is correct, but with relative humidity below 65% and a temperature above 20°C, it is possible to apply two coats per day. AITHON F3 (finish coat) can be applied the day after the last coat of AITHON PV33.


Storage and transport at min. 5°C and max 30°C. Unopened packaging has an 18-month shelf life. Opened packaging must be sealed carefully.


Once the treatment has been applied including protective top seal, it will last for the useful life of the substrate. Local mechanical damage should be immediately repaired following the application method aforementioned.

Health and Safety

During application avoid contact with open wounds, eyes and mouth. Eyes and skin should be rinsed immediately with clean water. Safety goggles and gloves should be worn when handling and applying the material. Adequate ventilation and appropriate mask required when spraying. More detailed information can be found in the Material Safety Data Sheet.

Our Services

We Do More Than Just
Concrete Fire Protection

Concrete Fire Protection

Timber Glulam Fire Protection

Steel Intumescent Paint Protection

Commercial Construction

Fire Compartmentation

Fire Doors

Fire Resistant Wall Covering

Fire Barriers & Curtains

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