The Importance of Dehazing
Most screens are ready for recoating at this stage, but sometimes screens will have to undergo a further step in the reclaiming process called dehazing. This additional step removes haze or ghost images left behind in the screen once the stencil has been removed. These haze images tend to faintly outline the open areas of previous stencils— hence the name ghosts. They are the result of ink residue trapped in the mesh, often in the knuckles of the mesh (points where threads overlap).
Dehazing is not something you automatically do every time a screen is reclaimed. In fact, it probably isn’t necessary unless the ghosts have become so prominent they are likely to interfere with exposing a new stencil. The best way to avoid having to dehaze your screens is to prevent ghosts from forming in the first place. As haze is formed by ink residue, simply doing a thorough job of ink cleanup can make all the difference. Sometimes that may not be enough to prevent your screens from having haze when you are printing with certain types of ink, especially those containing dark pigments.
After dehazing a screen, it’s usually not necessary to degrease it. Most dehazers do an excellent job of removing oils from the mesh. Always be sure to rinse the screen well afterwards. You don’t want any traces of dehazer left behind.