Varnish, or Oil?

There are two basic finishing approaches for wood that stays outdoors. Many brands use varnish on their products because first-day gloss is high and it is visually impressive straight from the factory. As a maker we prefer Italian Teak oil — in this guide we explain the technical reasons and the long-term comparison.

Varnish is a surface film, oil works into the wood. This basic difference determines everything in the long run: varnish blisters in 2-4 years, leaks water into the wood and requires a full restoration; oil works for 15+ years with an annual refresh. For wood that stays outdoors continuously, like a garden swing, the right choice is oil — especially the standard of a tung + linseed oil based Italian Teak oil. Varnish may be reasonable for an enclosed space (an indoor table); for outdoors it means short-term looks + a long-term problem.

1. Varnish: Surface Film Theory

Varnish is not actually bonded to the wood; it is a transparent plastic film sitting on top of the wood. Typical outdoor varnishes are acrylic, alkyd or polyurethane resin. On first application it forms a glossy, hard, waterproof layer — a very impressive look straight from the factory.

The problem starts over time. Three physical events fatigue the varnish film:

• UV degradation: Solar radiation breaks down the resin; the film becomes brittle, yellows, then cracks.
• Thermal expansion difference: Wood and varnish expand and contract at different rates. With the change of season the film develops micro-cracks.
• Moisture trapping: Once a crack forms, water gets under the film but cannot get out — the wood begins to rot; the film looks intact on the surface but the deterioration underneath is silent.

As a result, in Turkey's climate the outdoor varnish life is on average 2-4 years. After that the film must be stripped and the whole surface sanded from scratch + re-varnished. This restoration is a professional painter's job, hard to do in home conditions.

2. Oil: Penetration Theory

Oil is the opposite approach. It leaves no film on the surface; it works in between the wood fibres and dries and polymerises inside. Good formulas use a linseed oil + tung oil mix: linseed oil provides deep penetration, tung oil contributes UV resistance and hardening.

This approach has three important advantages:

• The wood breathes: Seasonal moisture balancing is not prevented; the wood expands and contracts but is protected from within.
• Cumulative protection: At the annual refresh new oil is added on top of the previous coat; the old one need not be stripped. With each application the depth increases.
• Local repair is easy: If staining occurs at one point, oil is refreshed at that point; there is no need to renew the whole surface.

Visually, oiled wood has a matte or light satin tone; it brings out the wood's natural texture. It is not as glossy as varnish but the “wood shows” — this aligns with most customers' preference.

The difference in one table

Why Deniz Salıncak uses oil

As a maker, using varnish would have given us two short-term advantages: factory-exit gloss + a first-day “brand-new product” feel. These two advantages would have worked well at sale.

But for a product that will stay outdoors for 5-15 years, a short-term finish is a long-term customer loss. A varnished swing flakes off like a peel in front of the customer after 3 years, and unless we are talking, the customer moves to a rival brand. An oiled swing is still like new after 3 years, and the customer returns to us later.

Italian Teak oil — tung + linseed oil based, UV stabilised, silicone-free formula — is the standard we have used since 2000. Its only side effect: it needs 2 hours of maintenance a year. In return for this investment the product life more than doubles.

Oil chosen. A 15-year investment.

Solid Iroko + Italian Teak oil standard. Protection that works into the wood instead of varnish. 15+ years with 2 hours of maintenance a year. 2-year warranty, free shipping to all 81 provinces.