Do You Ever Have To Strain Your Emulsion?

[Itsa Little CrOoked]

I don't remember seeing a thread on this, which seems odd. 

Yesterday, I filled a scoop coater with WR25 and found some lumpy stuff after a handful of screens. It was sort of like curds.  I had just added the Diazo an hour before.

So I got a wire framed tea strainer and ran the whole batch through it, then it worked normally.  I've had to strain it before (with Ulano QT Discharge or QX1) if I wound up with a half coater full and scraped it back in the bucket.  But out of a new container, yesterday was a first.

Which begs the question:  Do any of you guys strain yours?

Stan

[3Deep]

Sounds pretty much like it was not mixed very well from the factory or it got trash in it somewhere alone the line, but to answer your question, never...unless I got trash in it.

Darryl

[Doug B]

  44 years in the business and I have never heard of it. I have had some
go lumpy when it was too old. Then it wouldn't work at all.

[Sbrem]

Yes, something isn't mixed correctly. Are you sure you dissolved all of the diazo sensitizer before you added it? If so, and the lumps are in the emulsion itself, kind of like oatmeal, then maybe it's old, or got frozen somewhere along the way...

Steve

[ScreenFoo]

It didn't get frozen, did it?

[cbjamel]

Frozen is what it sounds like, i have had emulsion to close to the back of refrigerator and had it happen to be.

Shane

[Itsa Little CrOoked]

Diazo was mixed like I've done for years. It wasn't the diazo. It was clearly the polymer. No, it wasnt frozen, but I've been warned about going below 50 farenheit in storage. That is possible, but I never actually believed it.

No, the emulsion isn't old.

[Itsa Little CrOoked]

To keep the emulsion fresh I sometimes divide a fresh gallon of pre-sensitized emulsion into 2 or 4 parts with the diazo also divided.  (I have a scale that weighs to 1/100th of a gram, so the diazo IS accruately divided.) This practice is questionable depending on who you ask, but I don't think it could give rise to the lumps I saw yesterday. And my sensitized emulsion never sits for more than a few days this way.

There is, however, the possibility that introducing a little air into the top of a quart deli container of emulsion--prior to sensitizing--might be the culprit...  I just don't think so.  The process is done quickly, and sealed immediately after dividing. I sensitize the individual containers about an hour prior to use. I thought it was worth mentioning.

After I strained the 4 or 5 soft "curds" out of the emulsion, the application went smoothly as expected.  I've run a few jobs with this batch of dried screens and no problems have occurred.  All is well.

[Itsa Little CrOoked]

  44 years in the business and I have never heard of it. I have had some
go lumpy when it was too old. Then it wouldn't work at all.

I used to strain what I returned to the bucket everytime, but I stopped scraping the parts that had clearly begun to skin and the problem pretty much cleared up. Nowadays, I rarely return any. But other than that, this is the first time I've experienced the lumps also.

By the way...I LOVED "Lost In Space" as a kid!