# Why do I need emulsion remover?



## meazlesgolf (Mar 17, 2010)

Hey guys,

I am new to screening but I've read where someone used bleach to remove emulsion.

I bought a plastic tub that was big enough to lay my screens in for about $12 at Wal-Mart.

I put enough hot water on top of my screens to cover them by an eight of an inch; the water included about a cup of bleach before I put the screens in (don't know if it matters).

It just so happen that I had to make a run that took over an hour to do so, when I got back I took a scrub sponge and literally just "WIPED", not scrubbed but wipe the emulsion away and my screens looked almost new!!!!

My only concern and/or question is if the bleach is slowly or even quickly deteriorating my screen.

Anybody know? I find it very hard to believe that this is not the common practice of removing emulsion since it is so cheap if it is not somehow hurting the screens.


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## werdizthaword (May 13, 2008)

interesting....i would think so since bleach is such abrasive chemical...i know it corrodes metal...but honestly dont know....very good question IMO


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## InkedApparel (Mar 18, 2009)

I dont know..I use emulsion remover ..have never used bleach...I guess time will tell if the bleach is hurting the screen material.let me know in a month if your screen is still in 1 piece 
if so maybe I will switch to bleach.

Inked


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## meazlesgolf (Mar 17, 2010)

You got a deal!

I saw no apparent damage after I rinsed the screens but like you suggested, I plan to report back in a month or so of my findings. I also plan to pull some shirts this weekend and perhaps as early as Friday evening (3-26-10).


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## m_short (Nov 3, 2009)

meazlesgolf said:


> You got a deal!
> 
> I saw no apparent damage after I rinsed the screens but like you suggested, I plan to report back in a month or so of my findings. I also plan to pull some shirts this weekend and perhaps as early as Friday evening (3-26-10).


Have you tested the newtons of the screen before and after? It might be interesting to see if the bleach might have an effect that way over time.


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## RichardGreaves (Nov 7, 2006)

*Bleach is inferior to periodate chemicals*

There's nothing for bleach to oxidize on polyester so it does nothing to mesh. Polyester mesh wouldn't be any good for printing aggressive inks for metal, glass & vinyl if it couldn't stand up to bleach. 

There are dozens of posts on using bleach in this forum. Search for bleach, but skip the "printing" posts for this subject.

*Bleach*
I don't want you to use bleach. Bleach is slower, more damaging to the environment, smells and, most importantly, considerably less reliable than commercial stencil removers because the concentration must be exact for it to work and it varies from emulsion to emulsion. Grocery bleach is notoriously too low in concentration, and there's no effect especially if you spray the stencil with water first, diluting the action.

Water or solvent resistance of a stencil depends on the complete cross-linking of the ingredients by the sensitizer with UV energy. If the exposure time is too short, or UV energy doesn't move all the way through the stencil, the cross-linking is incomplete, and complete resistance isn't achieved.

UV energy reacts with diazo or photopolymer sensitizer in the stencil and causes a chemical cross-link between the two components that make up the "emulsion". Linked together, and woven in and out of your mesh, the exposed/cured/hardened stencil will not dissolve with water and rinse own the drain.

Industrial stencil removers use Sodium MetaPeriodate (SMP, CAS 7790-28-5), or periodic acid mixtures to attack these cross-links, releasing and breaking down the stencil so it will dissolve, and you can reclaim the mesh and coat it again.

If you let this 'soup' of stencil remover & emulsion dry on the mesh before you can rinse them down the drain, they form a new chemical bond that is permanent.

There is no chemical to break down this chemical combination except the brute force of water pressure. Yes you will also lose mesh tension blasting the mesh as it vibrates like a drum, if the stencil doesn't come out. If you use 3,000 psi water, you don't even need a chemical to breakdown your stencil, but it helps to have tight mesh to resist the pulsing water from a pressure washer.

This hard to reclaim effect also happens with under-exposed stencils. No cross-links - hard to reclaim.

A stencil may have worked OK with harmless plastisol, but if you clean the ink with a strong solvent, the solvent can attack the defenseless under-exposed stencil and chemically bond it to the mesh that only a razor blade can fix.


Bleach _is used_ to remove gelatin indirect stencils, but bleach is inferior to SMP for breaking UV cross-linked diazo or SBQ. It takes more bleach to do the work of a small amount of SMP.

Many will answer, "but it works", this is a classic do you have time or money question.

When you go home I want you to use a key to open your front door, not the kick of brute force.


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## meazlesgolf (Mar 17, 2010)

*Re: Bleach is inferior to periodate chemicals*



RichardGreaves said:


> There's nothing for bleach to oxidize on polyester so it does nothing to mesh. ........


WOW! That was pretty deep but I understand; Thank you!


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