Emulsion Coating problems

[derekprins]

I am not sure if this is the right place for this topic, but here goes. I am using a scoop coater to coat my screens. When I coat a 110 mesh it coats perfectly but when I coat a 230 mesh, the centre portion of the screen is coated much thicker than the outer edges. This means that the centre section of the screen has a much thicker layer of enulsion, so much so that it does not even dry properly. When I expose the screen, the image in the outer areas doesn't wash out becuase it seems hopelessly over-exposed, while in the center are, the emulsion just simply washes away becuase it is not even cured properly. What am I doing wrong? I use the same emulsion and the same coating speed/tempo for all screens.

[ApeShirt]

That seems to be a very strange problem. I hope someone has an answer as I am very curious about this. I personally have never had that problem.

[Saati]

I am not sure if this is the right place for this topic, but here goes. I am using a scoop coater to coat my screens. When I coat a 110 mesh it coats perfectly but when I coat a 230 mesh, the centre portion of the screen is coated much thicker than the outer edges. This means that the centre section of the screen has a much thicker layer of enulsion, so much so that it does not even dry properly. When I expose the screen, the image in the outer areas doesn't wash out becuase it seems hopelessly over-exposed, while in the center are, the emulsion just simply washes away becuase it is not even cured properly. What am I doing wrong? I use the same emulsion and the same coating speed/tempo for all screens.

Typically puddling in the center of the screen means the screen tension is uneaven. If you feel it is ok then you will need to apply more inward force while coating.

[drew]

I would have never thought of that but now that you mention it, it makes perfect sense. Thank you Saati.

[derekprins]

The tension is definitely even. Thanks for the advice about the pressure. I'll give it a go, it makes sense actually. Thanks again Saati

[derekprins]

Just a quick update. I coated two screens last night and used more inward pressure as you suggested and it coated perfectly. Thanks Saati!

[Saati]

Just a quick update. I coated two screens last night and used more inward pressure as you suggested and it coated perfectly. Thanks Saati!

No worries. If you run into any more issues dont hesitate to ask. We are here to help cut the learning curve down a little.

[ApeShirt]

Seems strange that you are using enough pressure on the different mesh counts.