SAATI turned my UV thinking upside down!

[blue moon]

'participated in a conversation Richard had with Ross at SAATI and my exposure thinking has been turned upside down. The wavelength, times, evaluating the exposure and what is really going on is waay off from what I was thinking.

This was a private conversation with request not to share (sorry for being Tony here), but it is looking like the UV wavelengths we were previously discussing are off by a bit, that more power in some cases is not better, that Photopolymers have some significant issues with proper exposure (which explains why they are not water resistant). A bit of data and scientific explanations were shared that left both Richard and myself scratching heads. Even he admits that it put a lot of his understanding of emulsions and UV (and this is from the guy who was product developer at an emulsion manufacturer) in question. Further research is needed to confirm what was said, but so far all the little quirks of the stencil making are fitting in.

WOW!

pierre

[blue moon]

p.s. I should ad that this does not make any of the UV lights obsolete or non functional, but there seems to be a better way (which includes both the lights and the emulsion)

[mk162]

your vagueness is impeccable...

[jvanick]

I am reading in between the lines and seeing a conspiracy starting.  Lol.  *ducking*

[GKitson]

Wow, Ross & Pierre in a conversation with Greaves acting as what, the translator? 

Ross really, really, really, really knows his stuff and I think I had a similar conversation with him recently, making me rethink also.

~Kitson

[Orion]

So what else is there to know, that can not be found in this article, penned by Mr. Balfour?

[jsheridan]

I was there when the convo happened and it makes perfect sense.

[jsheridan]

On another side of the UV industry.

The commercial growing industry is exploding with LED grow lights and that's an awesome thing for us as we'll get the trickle down cost effect for they use some of the same wavelengths as we do for vegetation phase.

[blue moon]

So what else is there to know, that can not be found in this article, penned by Mr. Balfour?

yes, that's a good part of it. It is a good read and should be checked out. The wavelength seems to be different from what's mentioned here though.
There's also a show report by Richard and Scott that add few more elements of the conversation. It can be seen here:
Richard and Scott report


pierre

[Itsa Little CrOoked]

So what else is there to know, that can not be found in this article, penned by Mr. Balfour?

yes, that's a good part of it. It is a good read and should be checked out. The wavelength seems to be different from what's mentioned here though.
There's also a show report by Richard and Scott that add few more elements of the conversation. It can be seen here:
Richard and Scott report

pierre

Watched it on my notsosmartphone in its entirety at 2-3:15ish AM. Actually, my phone is smart enough. It's me who's not so smart.  I'll be dozing off at my desk later today. 

I was definitely intrigued as to WHY certain unnamed mfg firms wouldn't let Richard use his UV meter.

Must be a deep dark secret yet to be fully disclosed, I reckon. And I'm in the market for an exposure unit in the not-too-distant future. I'm cobbling up a undersized NuArc 2125 in the interim.

[Orion]

Thanks for that link Pierre. As long as I have been doing this, there is still a ton of stuff I don't know. Sad thing is, there is a lot of information available that is just incorrect. For instance, just yesterday I came across four different formulas for determining smallest printable dot. All four formulas came from reputable sources, so which one is right? Another thing I found on an emulsion mfg. website is to dry a screen squeegee side down to boost abrasion resistance for wb/dc printing. WTH?

Anyhow, this uv wavelength you are speaking of, is that for pure photopolymers only?

[blue moon]

Thanks for that link Pierre. As long as I have been doing this, there is still a ton of stuff I don't know. Sad thing is, there is a lot of information available that is just incorrect. For instance, just yesterday I came across four different formulas for determining smallest printable dot. All four formulas came from reputable sources, so which one is right? Another thing I found on an emulsion mfg. website is to dry a screen squeegee side down to boost abrasion resistance for wb/dc printing. WTH?

Anyhow, this uv wavelength you are speaking of, is that for pure photopolymers only?

it is probably more pertinent to the SBQs, but will apply to all of it.

pierre

[jsheridan]

I came across four different formulas for determining smallest printable dot. All four formulas came from reputable sources, so which one is right?

The one that after testing on your mesh, prints the smallest dot.

thanks to the wide variety of mesh counts and thread diameters, we the end user have to take those formulas and tweak here and there to fit our applications.

[mimosatexas]

dry a screen squeegee side down to boost abrasion resistance for wb/dc printing.

A little off topic, but I started doing this as a test when I was using hardened Aquasol HV for my discharge printing and it UNDOUBTEDLY made the stencil last longer than drying the coated screens the traditional way.  I have switched back to just drying the traditional way since switching to SP1400 for basically everything so screens are good to go for plastisol and waterbased interchangeably because the SP1400 just doesnt have breakdown issues for the size runs I currently do, but it definitely works for weaker emulsions.

For my one color white/glitter plastisol jobs I still use HVP simply because it exposes faster on those thick coated low mesh screens, again dried the traditional way.

[blue moon]

we have been post exposing the discharge screens and are currently printing runs up to a 3,000 pieces without any hardeners.
As explained in the article Orion linked to (and part of the conversation in LB), SBQ does not fully crosslink even if exposed properly. Washing it out reorganizes the molecules and allows for second exposure to be very effective.

pierre