Paint thinner

A paint thinner is a diluent, also called a solvent, used to dilute oil-based paints and water-based paints — and similar things, such as varnish, which in essence are a colloidal suspension of a solid dispersed in a liquid medium — to reduce the viscosity and so making them "more liquid", in this context, to dilute is also known as to "thin".

Solvents labelled "paint thinner" are usually white or mineral spirits for oil paints whereas water is the primary solvent of water-based paints.

Uses

After a long period in storage, paint can lose some of its solvent, so can become too thick and dried-out for use, but can be restored to use by the addition of a diluent.

These solvents can also be used as in a paint-brush cleaner to remove or clean items that have become caked in paint.

Common paint thinners

Common solvents historically used as paint thinners include:

• White spirit, also called mineral spirits
• Acetone, often called nail varnish remover
• Turpentine
• Naphtha
• Toluene
• Lacquer thinner
• Methyl ethyl ketone (MEK)
• Dimethylformamide (DMF)
• Glycol ethers, such as 2-Butoxyethanol

Less common solvents used as paint thinner, but still used in the construction industry include:

• Ethylbenzene
• Xylene
• n-Butyl acetate
• Butanol

Due to their hazardous nature, in recent decades, the usage of these solvents has been extensively reduced in favour of water-based paints — that is, paints that are formulated to be made with water as the solvent and 'thinner' — which also are much less polluting, so have a much lower environmental impact.

Health concerns

Some paint thinners can ignite from just a spark in relatively low temperatures. These solvents are often known as VOCs (volatile organic compounds), — with white or mineral spirits having a very low flash point at about 40 °C (104 °F), — the same as some popular brands of charcoal starter. All such solvents with low flash points are hazardous and must be labelled as flammable.

Extensive exposure to vapours created by paint containing these solvents or its clean-up are hazardous. For safety reasons, the use of substances containing these solvents should always be done in well-ventilated areas, to limit the health consequences and minimise the risk injuries or fatalities.

The American Conference of Governmental Industrial Hygienists has established threshold limit values (TLVs) for most of these compounds. The TLV is defined as the maximum concentration in air which can be breathed by a normal person — i.e. excluding children, pregnant women, etc. — in the course of 40 hours per week, (a typical American work week), day-after-day through their work life without long-term ill effects.

In countries with poor environmental protection regulation, workers commonly experience much higher exposure to these chemicals with consequent damage to their health.

Addiction

Paint thinners are often used as an inhalant, due to its accessibility and legality as a drug. Many teenagers become addicted to thinner and due to lack of knowledge, parents and caregivers do not notice it or give it much attention.

See also

• Environmental impact of paint
• Substance-induced psychosis