Checking for pinholes

[Maxie]

What light do you use for checking screens for pinholees.
I am using a table with a glass top with 2 fluoresents under it and it's not so easy to see the holes.
Has to be a better way.

[Frog]

I use a real light table with four or six tubes, I forget.
In the past in some shops, we merely held them up towards the ceiling lights.

Improved housekeeping and thicker EOM has really reduced mine since the ol' days.

[screenxpress]

^^^^^ What he said

I have a light table too, but I have found it more productive to hold the screen up towards the florescent lights in the ceiling as you can move the screen around and detect pinholes better than the light table.

I might just have a light table up for sale soon, lol.

[willy35]

I placed the light table vertically against a wall, we see every tiny holes.

[Maxie]

Wily you get 10 points, I like your idea. Thanks.

[tonypep]

What are these things you call pinholes?

[Sbrem]

When I used to touch up screens, I preferred a single tube over the diffuse light of a light table, it seemed to make them show up better, more contrast I believe.

Steve

[tonypep]

In all seriousness, the light table is not ideal. I've built a few "viewing boxes" with old school 40 bulbs around 4' away from a frosted mylar/glass surface. Its why you see printers hold the screens towards the ceiling lights checking for PHs. The flourescent bulb so close diffuses light and does not allow enough contrast.

[T Shirt Farmer]

Maxie

Once we went DTS and removed the glass from our exposure unit 99% of pin holes went away, so much so we do not even check for them prior to printing. I know you are trying to take your business to the next level a DTS will get you there so much quicker. As so many have expressed here the DTS has so many great things to better your production, many are small benefits on there own but cumulatively they are a game changer indeed.

[3Deep]

I just got done cleaning our exposure glass because we were getting to many pinholes and I'm thinking most of them are coming from our dirty glass, but I just hold my screens up to the light see just about everything.

[Prince Art]

I also just hold screens up to the light, or toward an open door.

Dirty glass is probably the number 1 source of ongoing pinholes. Second thing to watch is where you place your screens between reclaim & coat. Dust can often get on them in seemingly not-so-dirty places; all the more if they dry outside or near the floor. Before coating, I give screens a quick, light brush-off on each side, which helps remove bits of dust. With that, clean glass, and photopolymer emulsion, we rarely get pinholes.

[Maxie]

I was waiting for th DTS solution, sounds great it's a big investment right now.
Our holes are definitely from dust on the glass.
I set up a upright light today,bought a LED panel, I'll post photographs.

[ABuffington]

Coating too fast can also be a huge issue as it imparts bubbles behind the mesh knuckles that may not be visible now, but will breakthrough during printing.

[tonypep]

This is quite true of course, especially with mid to low mesh counts

[Frog]

Coating too fast can also be a huge issue as it imparts bubbles behind the mesh knuckles that may not be visible now, but will breakthrough during printing.

Absolutely true, but "bubble breakouts" , like fisheyes, are completely different screen making problems than pinholes, which are usually related to dust after coating, as pointed out.
I know that in some operations where we had housekeeping problems, we used tack rags to ensure that the screens themselves were cleaned before coating to prevent the delayed pinhole effect as these dust spots would break through during the run.