Care and feeding of Emulsion?

[ZooCity]

Does anyone else notice that when you get toward the bottom of a gallon of high-solids emulsion you get all kinds of nasty little chunks on the screens?  I wound up tossing nearly a quart out of my last gallon of Aquasol HV because of this. 

I buy our emulsion parsed out into gallons every time, even though I buy by the five gallon (actually I think Westar sells me four gallons at a time, which is easier to ship in a box probably) to prevent this but I'm starting to see it happen more in the gallon buckets.  And it's been unseasonably humid around here lately.  I keep our emulsion in a temp stable spot, away from sunlight, often in an old cooler actually so I don't think that's the issue.  I even wipe the insides of the bucket lightly with a damp rag to keep any chunkies from crudding up along the walls of the container and getting into the scoop coater.

My thought was to pickup a bunch of the black vapor lock quart containers, open the fresh bucket, stir the living hell out of it and then fill and seal the quarts.  Bonus would be, if you weighed them out properly,  you could add diazo to a single quart at a time if needed without dedicating a whole gallon. 

It must be that I'm evaporating off enough of the water in the emulsion that, by the time you get near the bottom of the bucket, it's partially drying. 

Anyone have a fix for this?

[mk162]

never had that problem, but couldn't you strain it back into a newer gallon?

[Frog]

never had that problem, but couldn't you strain it back into a newer gallon?

That could get messy.
When we used varnish die-stamping inks, we would have to strain through cheese cloth.
Would probably work for this.

[ebscreen]

Zoo, yes I have run into this. I store emulsion in a nice shady spot too, and still the bottom
of gallons get gnarly. Usually end up chucking the last pint or so. I think you're on track with
the evaporation idea, pretty sure that's the only way it could happen. Makes sense to, as it seems
worse on the high solids emulsions.

One trick I have with waterbased inks is to put a couple drops of water on the surface of the ink
before closing the lid. Not sure how that would work with emulsions though, wouldn't want
to introduce new variables.

What I'm looking for is 5 gallon pails of emulsion with pour spouts on the bottom. One way air
vent on top. Anyone make these?

[Colin]

What I found to be my problem was the emulsion on the sides and top of the container would dry out inbetween the times I needed to coat screens.  The longer the time between , sometimes as long as a week, I'd see more dry particles/chunks under the lid edge and on the sides.  These would usually get stirred back in if the person pouring the emulsion was not paying attention.  Conversely, the quicker I went through a container, the fewer chunks I would see. 

It became a habit of mine to always peel away dried emulsion when I found it.  As a result, I found fewer chuncks in my scoop coater at the end of the gallon.

If you have the oportunity, you can store the opened emulsion in a refridgerator.  That will slow down the drying/evaporation.

A side note: I always stored my un-opened emulsion containers upside down to make it easier to stir the solids back in when it had been sitting for a month or so (I'd always buy two at a time or pour off from a 5 gallon depending). 

Hope this helps.

[Evo]

Good Cooks brand silicone one-piece spatulas. Best thing ever for emulsion and wb ink, totally smooth with no crevices for gunk to get into.






First, after I mix the emulsion I take the lid and clean it thoroughly to remove any excess that will dry up.

After coating screens, scrape the inside of the bucket with the spatula all the way down to where the emulsion is every time. Wipe off the top lip with a clean damp rag before putting the (clean) lid back on.

Always pour from one side of the bucket to avoid buildup along the whole edge. (I pour from the opposite side of the label so I can still read what it is and when it was dated)

If you know you will not coat for a week or more, spritz the inside of the bucket with one or two light sprays of DISTILLED water. Make sure to stir completely next time you open it.

[ZooCity]

Darn good ideas everyone.  I'm going to use them all I think.  I'm not sold on straining it, like Frog says, sounds messy.  But the spatula is smart and I had pondered adding water but Jason, yer right, it better be distilled water. 

I think breaking it down into the quarts should almost solve it too.  We tear through enough of it that a quart shouldn't last anywhere near long enough to get the chunks.  I think we only get around 30 screens or so out of a gallon and that's close to what we're running through every week and half or so.  Using the distilled water mist and good "industrial hygiene" should give it even less of a chance. Or at least, if things do get gnarly it's going to be a lot less emulsion at the bottom of the quart that I'm tossing out. 

What I'm looking for is 5 gallon pails of emulsion with pour spouts on the bottom. One way air
vent on top. Anyone make these?

Yes!  That is exactly what I want.

[Evo]

What I'm looking for is 5 gallon pails of emulsion with pour spouts on the bottom. One way air
vent on top. Anyone make these?

This is probably the best you could hope for:

http://www.screenprintingsupplies.com/Ulano_EM5G.htm

[mooseman]

we use Ulno QTX and see the same condition at the bucket bottom.
We add a little water, stir the snot out of it add more water if we think it needs it and add to the the mix  about the same amount from a new bucket and it seems to work just fine.  Fill the coater and work away. Left over stuff all goes into the new bucket all is good as far as we know .
mooseman

[jsheridan]

I always use two buckets.

When I mix a brand new gallon I  pour off half into the empty one I just finished using. This way I'm never pouring more than 1/2 bucket into a coater and the emulsion stays fresher.

[ZooCity]

What I'm looking for is 5 gallon pails of emulsion with pour spouts on the bottom. One way air
vent on top. Anyone make these?

This is probably the best you could hope for:

http://www.screenprintingsupplies.com/Ulano_EM5G.htm

Yeah but with all that air in the 5 gal bucket I could see the same problem coming up right?

[squeegee]

I know the little chunks you are talking about and always pour from a clean edge or wipe down the edge with a wet rag if needed.  I also give the emulsion a stir when I see those liitle chunks on the surface to try and minimize their concentration in the scoops.  When I see those chunks on a dry screen, which I normally spot from the squeegee side, I always look at the print side, I look for a reflection off the emulsion to see if the chunks are really affecting the print side and most of the time they aren't.

[blue moon]

hmmm, interesting . . . For the most part, I vary rarely encounter any garbage on the bottom of the bucket.
here's what we do, not sure if any of it makes any difference though . . .
-always have at least a third of the bucket full. It seems like the smaller quantities dry faster (more air in the bucket?)
-keep the air tight lid closed when done coating. Making sure it is fully sealed.
-wipe off any emulsion of the side/edges after pouring and keep the outside spotless. Inside usually builds up, but as long as the edges are clean it does not flake off, just builds up on itself.
-what ever does not come out easily at the end, we discard (a very small amount as I'll angle the bucket and let is sit while I coat. Maybe half an inch on the bottom, possibly less).

We do go through a bucket every three days, so that might help, too. I have tried splitting the buckets as John suggested, but did not see any improvement.

we also use Aquasolv HV.

I would not add any water or anything else to the emulsion as it will change the exposure times and EOM.

[ZooCity]

We do go through a bucket every three days, so that might help, too.

I'll bet it does.  If you're tearing through it at that rate there's probably not enough time for anything to dry up and be problematic so dividing it up wouldn't make a difference.  Your emulsion is probably really consistent because of this. 

Now, take a shop like ours or smaller using a gallon every couple of weeks and I would imagine by the bottom of the bucket in the second week the emulsion officially has a lot less water than when it started out.  As hesitant as I am to add anything to emulsion, I think just a little spritz of distilled water is better than having overly thick emulsion.