Sanding and refinishing a timber floor causes disruption, 'how much' disruption is a common question from both domestic and commercial customers alike. Having floors restored can mean moving out, and in commercial applications even loss of revenue. So here we address this and other concerns to be understood.

The subject of health and safety is one that is never far from the headlines in news and social media. Whether it's talk of microplastics, ‘forever chemicals’ or added chemicals in highly processed foods, there are always discussions and views being aired. Home owners can easily search information on the internet, meaning they are better informed about product choices. The chemicals and solvents used in flooring industry products are no different and have a direct impact on the amount of disruption that refinishing a timber floor causes.

The chemicals and solvents used in flooring products not only affects disruption but is also a compliance issue. Flooring products are under are under more and more scrutiny from specifiers and homeowners for compliance with Standards and Codes. Some standards, which you may have seen on datasheets, require products to meet limits regarding solvent content, like A+ Emissions (FR), EMICODE, DIBt & AgBB (DE) and Greenguard (US). Others like LEED, BREEAM, Living Building Challenge and GreenStar have both solvent restrictions and restrictions on the raw materials within the products together, in some cases, with other restrictions. There is also a growing movement requiring products to have an environmental product declaration (EPD) which details the environmental impact of a product or material throughout its lifecycle.

When it comes to your working methods and product choices, it is important to be transparent when quoting to disclose the products used and their environmental or health impacts. You have a Duty of Care under the law to all people who are present on the site during or after any works carried out by you. That includes other workers onsite and of course the customer.

Using Bona water-based polyurethane finishes and/or in combination with Bona dustless sanding DCS is compliant with or exceeds Australian standards. However, if using solvent based finishes you are required to protect you and your staff with PPE and advise others of the risks of solvent exposure & dust exposure etc. Protection against solvents for workers has been discussed many times and there is a lot of information available, both through the Australian Timber Flooring Association ATFA and independent on-line sources. The recent cases in relation to silica dust exposure should be a wake-up call as hardwood dust is a known carcinogen. Bona's DCS dust control system is rated to the highest H class requirement which picks up 99.996% of particles 0.0003 mm in size. This protects you, your staff and others on the site and reduces the amount of residual dust left to clean up.

The continued availability and use of products containing unsafe levels of solvents presents risks to both contractors and their customers, with proven studies detailing the adverse effects from solvent exposure. It directly affects the customer because the pervading solvent gases necessitate vacating the premises before reoccupation, ie the 'time before is it safe to make back in'. Our own industry ATFA documentation (Information Sheet 91) looks in depth at the subject of offgassing which effectively illustrates the key points:

• The escape / dispersion of volatile solvents and other solvent fractions occurs during the drying / curing phase. This can take days or in some cases many weeks.
• If you can still smell the solvents, then the process is still taking place, and sometimes that can be the case even without there being a noticeable odour.

What can affect the process?

• Site conditions – ventilation and temperature. As we all know, if it is cold and / or there is poor ventilation any drying / curing process takes longer and vice versa.
• Absorbency of the substrate / number of coats – basically the more product present, the longer it will take for the solvents to disperse.
• Time between coats and the site conditions during coating. With ventilation and longer intervals between coats the solvents disperse quicker as they aren't ‘trapped’ having to pass through subsequent coats.

Which brings us neatly back to the question – When can customers move back in?

If using a waterborne finish system, it is possible to advise clients they can stay in areas of the house away from the newly coated floors and / or move back in within a couple of days if larger areas are being coated. In commercial properties it is common for floors to be coated and the floor to be put into full commercial use 24 hours later, or sooner in some cases. When using solvent based coatings some documents advise 7 – 10 days or that it may take even longer before a property can be reoccupied. It is of serious concern that there is no widespread detailed advice available for solvent use considering the health and safety implications.

Even when colouring floors solvent based stains can be replaced with 2 component oils. Solvent stains typically have VOC levels over 500 g/Lt, whereas Bona's 2 component oils are around 25 g/Lt. The European directive of 2007 as adopted by ATFA sets an upper limit of 140 grams / Litre VOC content. Bona's waterborne finishes are around 50 g/Lt with the newest one component products for commercial floors at around 30 g/Lt, less than a quarter of the EU limit. Solvent finishes contain many times this level of solvent with figures of between 300 and 800 g/Lt not being uncommon.

Years ago, it was argued that solvent based products were superior in performance to waterborne finish systems. That has not been a valid argument for many years with waterborne systems now being the superior choice. Bona waterborne finishes are used on commercial floors ranging from restaurants, pubs and clubs to The Sydney Opera House and the National Portrait Gallery, shops, sports floors, houses and even heritage listed railway station waiting rooms. The health and safety implications for contractors and customers together with the convenience of being able to move back quickly into rooms with freshly refinished timber floors means that waterborne finish systems is the clear and obvious choice.