how to confirm the dosage of the powder when printing is an unsolved problem till now. the powder couldn’t be less or more when printing, only the confirmed way is by experience. according to the existing experience, the below factors should be put into consideration.
1. the thickness of the ink layer
the thicker of the ink layer the more possibility of the dirtiness of the product when pasting, then the dosage of the powder should be more.
2. the height of the paper piled
when the paper was head up higher, the gap between the papers will be small, the power of binding between the ink layer and next paper molecule will be lager which will easily cause the dirtiness of the back cover of the product, so the dosage of the powder should be more.
3. the character of the paper
but, the art paper with rough surface, pink coated paper, acidic paper, opposite polarity electrostatic paper, paper full of water and paper without flat surface which are not easy for ink dryer, the dosage of the powder should be more.
so during our production, we need to be diligent of inspection to avoid the pasting dirtiness
4. the character of the ink
different kinds of ink with different elements and rates of connection material and pigments, surely not similar drying time, so the dosage of the powder should be different.
especially in the process of printing, we always adjust the suitable of the printing according to the production by adding some varnish viscosity reducer to low the viscosity of the ink which will lead the decrease of the ink cohesion and the longer of the ink dryer time, so the dosage of the powder will be more.
5. the ph value of the fountain solution
the lower ph value of the fountain solution, the more serious of the ink emulsification which will lead the longer time for the ink drying, so the dosage of the ink should be more.
6. the speed of printing
the faster of the printing which will lead to the shorten of press printing time, then the shorten of the ink permeation into the paper, the same time, the power flowing on the paper will be less. in this case, the dosage of the powder should be more.
when we’re printing some slap-up album of painting, sample and cover, as the character of the ink and paper is better , so only we should slower the printing speed which will save the dosage of the powder.
in a word, we should follow below 2 points,
look, the paper will put on the platform, if we can see a layer of powder easily, the we need attention, the dosage of the powder is rather big, it may effect the following process of surface treatment. we also should take up the paper and see through the negative direction light to inspect if the powder is suitable
touch, using the fingers to touch the blank site or the edge of the paper, if easily you can feel the powder then the dosage is rather big, if only small, to keep safe, we advise you can print 300-500pcs, 30minutes later, if no problem, you can proceed.
in order to decrease pollution of the production environment and the effect of the product quality and body healthy, we should control the dosage of the powder. and we advise the factories should purchase some recycle equipment of powder which can be installed above the cover plate of the paper chain.
the article is from the technical database for printing
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