Author Topic: Emulsions The basics and the details.  (Read 1334 times)

Offline Dottonedan

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Emulsions The basics and the details.
« on: September 08, 2015, 03:30:20 PM »
Richard Grieves, A Buffington or Larry Tywater, (Welcome Larry)...or any other Emulsion Tech/sales rep.
Not to be brand specific, but can you give us some details for the new people looking at emulsion types.
Can you give us the basic differences of each group. The groups of Pure Photopolymer and then also Dual Cures?

Pure Photopoly,
Benefits or it's place/what it's typically used for, variations of solid content, what that really means...and affects on cost.

Same for Dual Cures.

Thanks greatly.
Dan


Artist & high end separator, Owner of The Vinyl Hub, Owner of Dot-Tone-Designs, Past M&R Digital tech installer for I-Image machines. Over 35 yrs in the apparel industry. e-mail art@designsbydottone.com


Offline ABuffington

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Re: Emulsions The basics and the details.
« Reply #1 on: September 08, 2015, 04:16:27 PM »
Al from Murakami


Pure Photopolymers - Ok we introduced SBQ to the industry and pure photopolymers have some significant advantages.  Long shelf life, over a year, good in any temperature found in a shop, 100+ degrees doesn't phase it, much longer coated screen life in good light safe dark rooms.  Fast exposures, almost too fast on LED.  You can post expose the emulsion for added strength or weak exposure systems, for dual cures and diazo it just helps dry it with very little additional exposure benefit. Great for all types of printing.  No additives needed, comes ready to coat.  Know your emulsion over mesh percentage to control halftones or to increase ink deposit for athletic printing.  There are photopolymers for graphics as well as textile.  Washout is typically with a pressure washer, hard to see unexposed image after exposure, shows up when wet.  Pressure washer speeds up development.  Available for all ink systems

Dual Cures - described as the best of both worlds.  SBQ is fast, diazo has great resolution, combined you have the qualities of Pure Photopolymer and diazo.  Latitude of exposure is wider and more forgiving.  Halftones are easier to produce, washout is easier.  Screen life and pot life of the emulsion are in the diazo range, 4-6 weeks (2-3 months at 70 degrees) Coated screens use within 2 weeks.   Graphics uses Dual Cures quite often for wide lattitude exposure where precision halftone capture is needed.  While not impossible with dual cures or diazo pure photopolymers are typically used  for electronic printing where mesh bridging is crucial. Available for all ink systems

Diazo Emulsion - Diazo has a 4-6 week shelf life and 2 week screen life.  These 'pot and shelf life' are always quoted to represent emulsion at it's peak of sensitivity.  With proper storage you can extend the life a little.  Good resolution of halftones, longer exposures, but LED is quickly changing that.  Melts out of the screen during development.  Requires hardeners for agressive ink systems.  Diazo can be durable if coated and exposed well, but too many underexpose to get max halftones, brand dependent, some can be exposed  completely and develop well for more durable screens. Available for all ink systems.

Bi-chromate - This was used a long time ago and hopefully is illegal to use in any area.  High cancer risk, many horror stories about this stuff, kills downstream aquatic life when discharged.  Tough as nails but so dangerous it should never be used again. Sad to say I have countries I go to where it isn't outlawed yet and it wreaks major ecological damage.

« Last Edit: September 08, 2015, 04:19:47 PM by ABuffington »
Alan Buffington
Murakami Screen USA  - Technical Support and Sales
www.murakamiscreen.com

Offline brandon

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Re: Emulsions The basics and the details.
« Reply #2 on: September 08, 2015, 11:09:17 PM »
Great post Al. Thanks