Screen Coating

Many questions are asked about the method and amount of passes when applying emulsion. Frankly, do what you need to do to get an even smooth coating making sure your last “cleaning” pass is made on the “squeegee side” forcing the heavier coating to the “print side” as discussed previously under “Screen Drying”.

Fact: Capillary emulsion films are applied to the “print side” of a screen because that is the proper side to have the heaviest layer of emulsion on for reasons of proper exposure and printing. You need to achieve the same result using direct emulsions. Humidity and De-humidifier during screen making

Humidity is not a good thing. The idea is to remove water from the process not to introduce more. If it has never been explained before then let me tell you, most “de-humidifiers” don’t work, in fact, most introduce “more” humidity than they remove.

The small de-humidifiers that you buy at the local appliance store have such small fan motors that are over worked and they heat up. That heat causes the coil on the back of the unit to sweat. That sweat drips into the pan that you empty every day. Put your hand to the unit and tell me if you feel warm or cool air blowing out the back?
Seriously, do you think there is that much water in the air? If so we’d be fish and not printers.

Costing only a few hundred dollars more, large capable industrial disaster recovery style de-humidifiers work well. Rather then the alternative units, this is a good way to not only spend your money wisely but to get a proper job done. These units run cool to the touch meaning that the water they collect “is from the air”. Many have their own internal pumps as well.

I personally use an Oasis brand de-humidifier capable of pulling 6 gallons of atmospheric moisture in a 24-hour period of time. Used mainly for flood recovery, it is ideal for keeping the screen making room “dry”! If I collect 3 gallons of water from June to September that is a lot and it gets humid around here in July and August.

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