LCR Hallcrest is able to supply a range of materials that change either reversibly or permanently in response to exposure to water.

Irreversible Hydrochromic Inks

These water sensitive inks can be used to create a wide range of effects changing from a solid colour to colourless.

The irreversible hydrochromics are available in various colours. They have good colour strength. Exposure to water denatures the dye and the colour change is permanent if the water does not dry out on top of the print.

Substrates used can affect speed of response with prints on non-absorbent material generally changing more rapidly than substrates such as paper. Colour reversion after drying out is more likely with prints on non-absorbent material than on paper though.

Irreversible hydrochromics can also be affected by high levels of humidity and are not suitable for exposure to such conditions.


  • Solvent Based Flexographic
  • Water Based Flexographic
  • Water Based Screen Inks
  • Labels – custom made labels can be produced

Wet And Reveal Screen Ink

This is a water based screen ink which dries to give a white opaque print. When wet the ink film takes up water and becomes transparent allowing any print beneath to become visible. If the water dries out the opacity is regained and the original white print is restored.

A fairly heavy print is required, which essentially means the ink is supplied as a screen ink. More than one print may be required to obscure an underlying print. As the coating weight of wet & reveal ink is increased the transparency when wet can be reduced so careful tests should be carried out to determine optimum printing parameters. Careful choice of underlying text / patterns can help by selecting something that will be easier to hide.

Wet and Reveal Screen ink can be printed on various substrates such as paper, cards, print receptive plastics and even textiles. Tests should be carried out to determine suitability for the substrate and application chosen.

When a highly permanent print on textiles is required the dried wet and reveal print can be crosslinked by baking for 3 – 5 minutes at 130ºC.

Good results have been seen with prints on absorbent substrates without additional curing but if a crosslinked film is desired, but temperature treatment is not an option because of the choice of substrate, then chemical crosslinking agents such as aziridine may be employed.