Thermoguard Thermoproof Interior Fluid


Thermoguard Thermoproof Interior Fluid is a clear, colourless, penetrating Fire Protection with an optional functional Thermoguard Thermoproof Interior Sealer for wear, damp & UV resistance available in clear or woodstain colours.

VAT excluded

£106.80 Tax incl.


Thermoguard Thermoproof Interior Fluid

Thermoguard Thermoproof Interior Fluid is a clear, colourless, penetrating Fire Protection with an optional functional Thermoguard Thermoproof Interior Sealer for wear, damp & UV resistance available in clear or woodstain colours.

Intended Use

Fire protection fluid for porous internal wood.

Finish Options

  • Bare uncoated
  • Clear Sealed
  • Woodstain Sealed

How It Works

In a fire, Thermoproof Fluid reacts with the woods cells to create a flame & heat resistant barrier. Thermoguard Thermoproof Interior Sealer (optional) is a flame-retardant sealer.

Finish Options

  • Bare wood effect
  • Clear sealed - matt or satin
  • Woodstain* - matt or satin

*For available colours see Thermoguard Thermoproof Interior Sealer, also colour match service available.

UKAS Fire Test Standards

  • BS EN Class B s2 dO
  • Class O

Note: This product does not achieve 30 or 60min fire resistance.


  • Bare wood option - 1 coat Thermoguard Thermoproof Interior Fluid


  • Clear sealed finish:

1 coat Thermoproof + 1 coat Thermoguard Thermoproof Interior Sealer Clear**

Woodstain Finish:

1 coat Thermoproof + 1 or 2 coats Thermoguard Thermoproof Interior Sealer Woodstain**

*Resists light cleaning & handling.
**Allow Thermoproof to fully dry (min. 4 days) before applying any sealer.
***2nd coat for added UV protection, damp rooms or moderate cleaning.

NOTE: To check final effect, apply to test patch before application to entire area.


A Certificate of Supply can be issued on request for projects for insurance, Fire and Building Control Authority and Client Records.

Application Methods

Brush, Roller, Spray

Pack Sizes

  • Thermoproof Interior Fluid - 20m², 80m²
  • Clear + Woodstain Sealer - 20m², 80m²

Application Conditions

Apply to dry wood (Max. 16% moisture), above 5°C in dry conditions.

Limitations - Stained, Varnished or Painted Wood

  • For treatment with Thermoproof to be effective, it needs to be able to penetrate the wood.
  • Thermoproof can be applied over water-based penetrating wood dyes that do not seal or make the wood water-proof.
  • To fire protect painted wood, see Thermoguard Timbercoat.
  • To fire protect clear normal varnished wood, use Thermoguard Fire Varnish Basecoat & Thermoguard Fire Varnish Overcoat.
  • To fire protect external stained varnished, woodstained or other coated wood, contact Technical Dept.

New Fire Regulations & Tests Explained

  • The new fire standard BS EN test lasts 20 minutes with airflow replaces the old BS 476 tests which lasted 10 minutes and strangely restricted airflow.
  • The new standard for flamespread and heat release Class B replaces Class O.

The new BS EN tests also monitor -

  • Smoke & Gas “s” – s1 + s2 are none or very low & compliant levels, s3 = moderate , s4 = heavy smoke.
  • Flaming Droplets or Airborne particulates – dO is none, d1 = low, d2 = moderate, d3 = high levels.

Environment & User Friendly

Thermoproof Interior Fluid, Thermoproof Interior Clear & Woodstain Sealers are water-based and environment friendly.

Quality Assurance

Products Manufactured under ISO 9000.

IMPORTANT FIRE PRODUCTS NOTICE: The information displayed on this website should be used as a guide ONLY and our Technical Department should be contacted to obtain a tailored specification and any advice necessary before you place an order for fire protection products. Fire protection products are non-returnable except in accordance with Condition 8 of the Terms and ConditionsWe will not be held liable for any resulting damage to property, human life or monetary costs incurred due to the incorrect specification you have prepared or use of fire protection products caused by your negligence, including your failure to have contacted us to obtain the relevant advice/specification.

It is your responsibility to read the Product Data Sheets (available below) before you place an order and prior to application of the product. The content of this website is our best recommendation and is not advice. Coverage rates quoted are approximate, you agree that coverage depends on the condition of the substrate, surface absorption, texture and application method. We ALWAYS recommend a trial area is coated to ensure the product meets your requirements before use.

Product Details

Data sheet

Brush, Roller, Spray
Supplied in pre-measured packs to apply 1 coat to 20m² or 80m²
Touch Dry
2 Hours

Customer agrees that before placing an Order, Customer has read and understood the most up to date Product Data Sheet for the Product. Where we have access to the Product Data Sheet from the manufacturer, we will either provide a copy on request, or include a link to the Product Data Sheet available on the manufacturer’s website. Customer further agrees that we have no liability for any errors or omissions contained within the Product Data Sheets. For more information, please see our Terms & Conditions of Sale.

questions Tom on 2017-02-09 19:13:47
Question: Can you use on untreated timber and then cover with a stain products

Yes if you use Thermoproof Original which is a different product to Thermoproof Fluid. It is important to wait until all water in Thermoproof Original has all escap after application before overcoating. The cost is the same as Thermoproof Fluid but we do not offer this on the website so orders must be placed over the phone.

An alternative option to achieve a similar result would be;
Thermoguard Fire Varnish Basecoat +  EITHER
Internal -   1 coat of Thermoguard Fire Varnish Overcoat (Interior) - clear or mixed to woodstain shade.
External - 2 coats of Thermoguard Fire Varnish Overcoat (Exterior) - clear or mixed to woodstain shade.

Question about the product

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Thermoguard Thermoproof Interior Sealer

Thermoguard Thermoproof Interior Sealer is available in a matt or satin finish and is used as a protective coat to be applied over Thermoguard Thermoproof Interior Fluid where protection from wear, damp & UV resistance is required. Thermoguard Thermoproof Interior Sealer is available in clear or woodstain colours.

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