Two types of floor finish -- very different consequences
Solvent-based and water-based are the two main types of floor finishes available for timber floors. The key difference: solvent finishes use chemical solvents as the carrier for the polyurethane. Water-based finishes use water. That one difference changes the health risk, the smell, the look, and how soon people can use the floor.
Solvent-based polyurethane technology was developed in the 1950s. These products became the standard for coating timber floors because there were no better alternatives and the health risks of solvents and isocyanates were not understood. They are classified as poisons and carry serious health risks. In the EU and many other countries, solvent finishes are either banned or severely restricted. In Australia, contractors can still use them in private homes without informing customers of the health risks.
Water-based finishes are classified as non-toxic and are environmentally responsible. They use water as the carrier for polyurethane dispersions, providing wear performance equal to or better than solvent finishes while retaining the natural colour of the timber.
VOC levels -- the numbers tell the story
The main difference between the two types is the amount of Volatile Organic Compounds (VOCs) released as gases during the curing process. VOC gases are toxic and flammable.
Solvent finishes release 300-850 grams per litre of VOCs. Off-gassing continues for up to months after application.
Most Bona water-based finishes are below 80 g/Lt VOC and none exceed 90 g/Lt -- well under the strict EU standard of 140 g/Lt. The VOC level is so low it is considered harmless.
In Europe, where the EU controls VOC levels in building supplies, solvent-based finishes are illegal for commercial use. In Australia there is no such legislation. Contractors can use solvent finishes with no health warnings required to protect homeowners.
Health risks of solvent-based finishes
The health effects of solvent exposure have long been recognised. Solvent-based timber floor coatings are classified as toxic, carry serious health risks, and are harmful to the environment. They are dangerous not only to the person applying them but also to homeowners and other people in the building, particularly children and the elderly, who may be exposed to the fumes.
Short and long-term health effects of solvent exposure include:
- Chronic and acute asthma
- Clinical depression, aggressive behaviour
- Impaired fertility, neurocognitive development issues
- Memory loss, brain damage
- Peripheral nerve conditions
- Increased susceptibility to cancers
- Eye irritation and inflammation
- Respiratory irritation, bronchial sensitivity
- Liver disfunction and damage
- Dermatitis, dry cracked skin
Solvent fumes also contaminate foodstuffs in the fridge and pantry. Cleanup requires toxic chemicals. Homeowners should vacate the home for up to 14 days while the toxic fumes off-gas.
With water-based finishes: no toxic fumes, no effect on stored food, easy cleanup in water, no need to vacate the premises -- homeowners can remain in the house during application.
Appearance and performance comparison
Solvent finishes add an amber tone that deepens with age, eventually giving a dark yellow plastic look. They also become more brittle over time. Water-based finishes dry clear, are non-yellowing, and show the natural colour of the timber.
The wear resistance of modern water-based finishes equals or exceeds solvent-based products. The old argument that solvent wears better does not hold up against current technology. Water-based also dries faster between coats, cutting down the total job time.
Bona certifications and environmental credentials
Bona finishes are GREENGUARD indoor air quality certified -- safe for use around families and pets. GREENGUARD certification is only awarded to extremely low emitting products meeting strict criteria.
Bona water-based finishes are certified by DIBt (the German approvals body for building standards, used as the EU's main building construction directive) to meet strict EU standards for low VOC levels.
Bona finishes carry the EMICODE EC1 label -- the lowest emission class, awarded after testing at recognised institutions. Bona finishes are also NMP free. N-Methyl-2-Pyrrolidone (NMP) is a co-solvent used in some waterborne polyurethane dispersions that can cause painful skin and eye irritation.
Bona is accredited to ISO 14001 environmental management systems by BVQI and SWEDAC, the national environmental certification body in Sweden. Based in Sweden, Bona has been the world leader in non-toxic water-based finishes since pioneering the technology in 1979. Bona finishes protect millions of square metres of flooring in over 90 countries.
What the professionals say
"Why use a solvent finish? Water-based finishes look better, perform as well and there are no VOCs, so customers can stay in their house." -- Michael Law, Coastwide Sanding QLD
"I use water-based for the safety and health of my customers. Families can move back in straight after the final coat, unlike a solvent finish where they need to stay away for days." -- Larry Hill, Hillspec Flooring WA
"We are acutely aware of the dangers in sanding dust and toxic solvent-based coatings. We want to create the safest environment for our staff and customers. We turn down all solvent finish work." -- Gerardo Iacullo, Iacullo Timber Flooring ACT
"I won't do a solvent finish job even if I'm asked. Once I explain the negative impacts like ruining food and needing to stay away from their home for days while fumes dissipate, my customers see that water-based finishes are the better option." -- Liutus Gudiskis, Optimum Timber Flooring NSW
"I use water-based finishes for my own health, the environment and the look. There are a lot of reasons why I won't use solvent finishes." -- Darren Roberts, Aust Dustless Floorsanding VIC