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Washing Screens - Foam Everywhere, Help!

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#76515

Washing Screens - Foam Everywhere, Help! | 31 October, 2016

Hi All- I've got an old industrial dishwasher converted over to a screen wash. It's a closed system, one screen at a time. Total volume of about 10 gallons, no heater. RoHS solder.

This thing is foaming up like a rabid animal. The screens go in with some paste left on 'em, (operators can only remove so much manually) and the wash runs a 30 second cycle. Sprays from top and bottom. Nothing but water and Kyzen DF10 in it now, which doesn't seem to be working. Problem gets worse with the 2nd, 3rd, 4th cycle in a row until it's all over the floor.

I'm currently using Kyzen DF10 defoamer, which worked a couple years ago, but now it seems to do nothing. Even got a fresh jug sent over. Solderstoreonline sells Defoamer 35, but that works best in heated washes, mine's 70 degrees or so. I don't know of any product out there is designed for a room-temp screen wash.

Does anybody have a recommendation on a defoaming agent that won't harm screens and will work for me? Thanks.

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#76517

Washing Screens - Foam Everywhere, Help! | 1 November, 2016

Maybe you could try Zestron Vigon plus DF 30

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#76584

Washing Screens - Foam Everywhere, Help! | 9 November, 2016

> The screens go in with some paste left on 'em, (operators can only remove so much manually) >

That is BS. We clean our screens by hand ONLY and I am able to remove all of the solder using a 1" putty knife and Micro Care Alcohol-Enhanced Flux Remover wipes (MCC-PROWR) made by ProClean. Don't let lazy operators persuade you into thinking that it cannot be done.

If you must use the machine I cannot help you there, but if you call Kyzen they should be able to help you pick a product.

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#76587

Washing Screens - Foam Everywhere, Help! | 9 November, 2016

You're right. It is BS. I should have said "the operators are only WILLING to remove so much paste manually."

When I brought up my concerns about leftover paste with the powers that be, I was told in no ambiguous terms that the operators will not be changing their behavior. My job is simply to mitigate their disaster. It's a difficult situation.

Thanks for your help, though. I've been in tough with Kyzen and am waiting on a sample of their top-shelf defoamer. If there are any other factors or solutions you think I may be overlooking, don't hesitate to bring 'em up.

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#76595

Washing Screens - Foam Everywhere, Help! | 14 November, 2016

Just from my recently acquired experience working with wash chemistry.

Some will have issues with foaming as the concentration of wash chemistry goes down and the temperature of the wash goes down. Over a few washes you may be seeing a reduction in wash chemistry in solution that's causing the foaming.

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#76606

Washing Screens - Foam Everywhere, Help! | 18 November, 2016

Lazy operators empowered by management. Sounds like you may have some nepotism?

Since it falls to you to clean up someone else’s mess I have an idea for you. I once worked for a company that had a large wash sink with a hand sprayer very similar to what you would find in a restaurant’s kitchen.

We scraped off the majority of the paste with putty knives, then used the sprayer to blast the stencil with hot water. This dissolved the flux which allowed the solder to wash away. After a few going from the front of the stencil to the back a few timesthe stencil was completely clean. We would blast it with compressed air to dry it. This worked like a peach. The down side is that you have to design a trap to catch the solder while letting the water go by. It is not completely different from the way gold is sluiced. Our set-up was something like this: Dirty water water dumps into a bin about 12” long x8” widex4” deep on the left side. And there was an open pipe on the top of the right side that allowed water to flow out. The dissolved solder would collect in the “trap” and the water flowed on by.

If memory serves we were using water soluble flux paste, so I don’t know if it would work for any other types of flux-paste or not. The downside is that someone has to periodically clean out the trap so that it does not fill up and let the solder down the drain. We had our maintenance department do it monthly. It makes it stupid easy for the operators, so it should be well received by your operators

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