Maintenance guide for decking and sauna bench products

This guide applies to: Kaarna Kaarna+Noki Kelo Ruska

About maintenance in general

Charred wood is generally easy to care for and requires less upkeep than wood that has been only oiled. With proper care and correct maintenance, charred wood remains beautiful for decades.

This guide describes the maintenance of Bark, Bark+, Soot, Snagwood and Autumn Glow board products made from pine and spruce, used as decking and sauna benches.

Read the section that applies to your use case as well as the common finish section.

Maintenance: decking

Hiil’s decking products have brushed surfaces. Some are tinted, some untinted.

Keep the surface clean. Brush the deck regularly to remove debris such as needles, leaves and grass clippings. Organic matter traps moisture and can create a growing surface for algae, mould and decay.

Avoid standing water. Ensure water can drain from the deck surface. Also check that the substructure does not remain wet.

Inspect structures and fasteners. Regularly check the screws or nails. Tighten or replace loose parts. Make sure there are no moisture-trapping piles or structures under the deck.

Wash the surface lightly with water when needed. Hiil’s decking can be washed lightly with water. For brushed surfaces, plain water is often enough — no detergent. Avoid harsh chemicals or solvents.

Mind use. When moving heavy furniture, use felt pads or lift — do not drag.

Re-treatment of decking

All Hiil decking changes tone over time in outdoor conditions. The untinted surface (Bark) greys, and the tone of tinted surfaces (Bark+, Soot, Snagwood and Autumn Glow) fades from the original. Patination is an essential part of the product and is not damage. Tinted products retain their tone longer than their untinted counterparts thanks to the colour pigment.

A deck is under heavier stress than a façade: it is walked on, and rain and snow fall directly on the horizontal surface. The protection provided by the oil weakens gradually. How quickly depends on how much sun, rain and snow the surface receives and how much the deck is used. A surface under a roof, in shade and sheltered from rain experiences significantly less stress than one under open sky. The need for maintenance also depends on how much change in tone and patina you are happy to allow.

For this reason we do not give a fixed maintenance interval. You can expect the deck to need its first maintenance treatment within 5–10 years of installation. Inspect the deck regularly, especially sunny and exposed areas and walkways.

Maintenance treatment with oil may be due if:

the tone of a tinted surface has clearly faded and you want to keep the tone closer to the original
the surface on walkways has worn clearly faster than the rest of the deck
the surface has sustained a substantial area of damage

Re-oil the deck with the same special linseed oil used at the factory, and order the oil using the product’s surface name. Treat the affected areas as described in “Maintenance treatment”. If in doubt, please contact us.

Maintenance: sauna benches

Sauna benches are in direct skin contact and are exposed to heat, moisture and sweat. Their maintenance therefore differs from that of wall surfaces and decking.

Use a bench towel. A bench towel or regular towel protects the benches from sweat and dirt and reduces dark spots at the seating areas. When fresh, tinted surfaces (Bark+, Soot, Snagwood and Autumn Glow) may release colour pigment if rubbed hard. Use a bench towel especially during the first sessions on new benches.

Air the sauna after installation. Linseed oil oxidises on the surface of the product after installation, so the sauna should be aired after new benches have been installed.

Dry the sauna after use. Leave the sauna door or vent open after use so that the benches and structures can dry. Benches must not be left wet for long periods.

Wipe and wash the benches when needed. Wipe the benches lightly with a damp cloth. Wash them occasionally with lukewarm water and a mild, pH-neutral detergent, using a soft cloth or sponge. Use as little water as possible and rinse off the detergent so that none is left on the surface. Do not use a pressure washer, stiff brushes or harsh detergents.

Prevent stains from setting. Fragrance oils, scrubs and similar products used in the sauna can leave stains on the benches. Wipe off any spills immediately.

Re-treatment of sauna benches

Benches wear most at the seating areas and front edges. Heat, moisture and sweat gradually wear down the protection provided by the oil. The need for maintenance depends above all on how often the sauna is used, so we do not give a fixed maintenance interval.

Maintenance treatment with oil may be due if:

the bench surface feels dry or rough, especially at the seating areas
the surface has worn or faded clearly lighter than the rest
the surface has sustained a substantial area of damage

When oiling the benches:

Only treat benches that are cold and dry.
Apply a thin coat and wipe off all excess oil carefully so that none is left on the surface to transfer to skin or textiles.
Let the oil dry thoroughly before heating the sauna. Follow the drying time given by the oil manufacturer and air the sauna after treatment.
Never leave oily rags or sponges in the sauna or near the stove. See also “WARNING — risk of spontaneous combustion”.

If in doubt, please contact us.

Maintenance treatment

Use the same finish product that the factory originally applied. Hiil products are treated with special linseed oil. The oil shade depends on the surface — order maintenance oil using the product’s surface name. If you are uncertain, ask us for a suitable finish and more detailed instructions.

Always follow the instructions of the finish product. Test the maintenance treatment on a small area in an inconspicuous spot before treating the visible surfaces more widely. Wipe off any excess finish that the surface has not absorbed.

Protect sensitive surfaces from possible oil splashes and drips (paving, floors, plinths, windows, etc.).

Note that in direct sunlight or on a hot day, oils can dry too quickly. The oil then does not have time to soak into the product adequately, and proper protection does not form.

WARNING — risk of spontaneous combustion

WARNING! Many drying natural oils pose a risk of spontaneous combustion.

Rags, sponges and sawdust soaked in oil can ignite spontaneously if left in a pile.

Lay rags and sponges flat to dry one by one outdoors on a hard surface, or submerge them in water — never leave them bundled in a bin.

Repairing surface damage

If damage occurs that breaks the factory-treated surface and exposes fresh, untreated wood, DO NOT repair the damage with a gas torch. Finish products generally do not tolerate fire and may ignite or smoulder.

The damaged spot should be re-oiled with the same product originally used on the surface.

Tips for successful surface treatment

Check conditions. Temperature +10…+25 °C and low direct sun are ideal. In too high temperatures the oil dries too quickly and does not absorb properly.
Use the original finish product. Re-treat with the same product that the surface was originally treated with.
Protect surroundings from possible splashes — paving, floors, plinths, windows.
Test first on a small, inconspicuous area to confirm the result.
Apply a thin, even coat and let the oil absorb. Wipe off any excess that the surface has not absorbed.

Re-use and disposal

All Hiil products are designed for long-term use lasting decades. If the products are dismantled for any reason, reuse the timber elsewhere if possible. This way the carbon bound in the product stays bound, the work that went into manufacturing remains useful, and the wood gets a new life.

All Hiil products contain only wood, linseed oil, and possibly a small amount of colour pigment. The finishes used in the products are not classified as hazardous. If you choose to dispose of the product, the timber can be used as an energy source.

Contact

Hiil Oy
info@hiil.fi
https://hiil.fi

Up-to-date contact information is available at hiil.fi.