How to Guide - Decoating Capillex
Screens can be reclaimed quickly and efficiently by using the right screen cleaning chemicals and techniques
There are three main steps to reclaiming a screen which if optimised, will make screen reclaiming an efficient and effective
Step 1 - Ink Removal
Assuming that the stencil is to be decoated and the screen reused for a new job the first step is to remove as much of the ink as possible. The most effective way to do this is with a screen wash which allows the ink residue to be rinsed off with water rather than having to use multiple applications of a cleaning solvent.
Note - contact your local water authority to determine what effluent restrictions there maybe. Always refer to appropriate Product Data Sheet for advice on the safe handling of screen solvents.
The MacDermid Autotype brush is perfect for applying screen wash as the soft fibres are resistant to solvents and the flagged fibre ends ensure good coverage.
Step 2 - Stencil Removal
There are several choices of stencil remover for Capillex; Autostrip Powder, a powder that is mixed with water, Autostrip Concentrate a choice of several concentrates that are diluted with water and Autostrip Gel, a ready to use gel. The choice of which one to use is dependent on personal preference, format, screen cleaning equipment and cost.
Link to Stencil Decoaters
Autostrip works best if it is applied to wet screen using a soft brush. Apply to both sides of the screen. Never allow to dry in and make sure the brush is rinsed clean immediately after use. If the decoater is allowed to dry in then it is almost impossible to remove! Always rinse off Autostrip before using the High Pressure Gun as this prevents atomising the stripper which could be breathed in by the operator and/or lead to pinholes if allowed to fall on cleaned screens.
Step 3 - Haze Removal
In most cases, a slight stain (Ghost image or Haze) remains on the mesh fibres after the stencil has been removed. The first step is to determine if it is an ink stain or a stencil/Diazo stain. If the image is the same as the printed image then it is an ink stain, however, if it is a negative of the printed image, then it is a stencil stain.
The best way to remove an ink stain is with solvent such as one of the screen washes.
Stencil stains, especially Diazo stains are best removed using a caustic haze remover.
In most cases though, the stain is a combination of ink, stencil and Diazo and therefore haze removers that use both solvent and caustic are the most efficient.
MacDermid Autotype offers three levels of Haze Remover (i) low caustic, (ii) medium caustic and (iii) high caustic.
The low caustic system used in Autokleen Plus is perfect for leaving on the mesh overnight and is used in conjunction with a screen wash to activate it prior to rinsing off.
The medium caustic used in Autopaste is perfect for general day to day use and also used in conjunction with a Screenwash.
The high caustic Autohaze is a one pot product and is designed for use with really stubborn stains. Caution - do not leave Autohaze on the mesh for more than a few minutes, otherwise it will damage the fibres.
Always first rinse the haze removal product off the screen using a low pressure spray and do not allow the screen to dry before using the high pressure gun. Always wear personal protective clothing when using caustic haze removers and refer to the appropriate Safety Data Sheet before use.