<P> The Tipp - Ex correction fluid is a white liquid . It is used for painting over mistakes in a piece of writing . A brush (which was later replaced by a foam applicator) is attached to the cap, so when the bottle is closed, the brush is immersed in the Tipp - Ex . When unscrewed, the brush is covered in liquid Tipp - Ex which is then painted over the mistake . However, it is still possible to see that Tipp - Ex has been used, and also the original content if the paper is held up to a light . </P> <P> If the contents of a Tipp - Ex bottle have been exposed to too much air (for example, if the cap has been unscrewed too long or if the bottle is half - full and there is air filling the space), the Tipp - Ex becomes thicker, and sometimes even solidifies . To help prevent this, Tipp - Ex released a product called "Tipp - Ex thinner", a few drops of which are mixed with the contents of a bottle of partially dried Tipp - Ex to thin it . This extends the lifetime of a Tipp - Ex bottle . </P> <P> One must write with a ball point pen on top of Tipp - ex, as a liquid ink pen will smudge . Gel ink will require some seconds to fully dry, but can be used if no ball point pen is available . </P> <P> The organic solvent 1, 1, 1 - trichloroethane was originally used as a thinner in the product . This solvent is readily absorbed by the lungs via inhalation . It passes readily through the blood--brain barrier and may be lethal following acute exposure . 1, 1, 1 - trichloroethane is also an' ozone depleter', being one of the substances responsible for causing damage to the Earth's ozone layer . For both reasons, it has not been added to Tipp - Ex since 2000, and it has been replaced by aliphatic hydrocarbons . </P>

When was tippex first used in the uk