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Powder Printing

For discussion and commentary regarding the Lesson and Project videos of the Bullseye Kiln-Glass Education Online program.

Powder Printing

Postby Chris_Petrauskas » Wed May 01, 2013 2:21 pm

Watch the Lesson at:
https://videos.bullseyeglass.com/videos/powder-printing/

Please discuss and comment in this thread.

Thanks!
Chris Petrauskas
Bullseye Glass Co.
Portland, Oregon, USA
http://www.bullseyeglass.com
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Re: Powder Printing

Postby cary.meiners » Fri Jun 14, 2013 10:53 am

Hi Chris-

I am very excited about trying this process. I am not able to find a yellow mesh screen with 137 mesh count. I have found a white mesh screen with 130 count. I don't know the significance of the screen color. It was stated in the tutorial that screen sizes between 110-195 could be used but that 137 was perfect. Where did you find 137? Is a variance of 10 significant? Would we than be using a different grade of frit or would it still be powder?

Thank you so much. For those of us in the boonies, this type of education is a true gift.

-Cary
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Re: Powder Printing

Postby jdepaula » Wed Jul 31, 2013 8:11 am

cary.meiners@gmail.com wrote:Hi Chris-

I am very excited about trying this process. I am not able to find a yellow mesh screen with 137 mesh count. I have found a white mesh screen with 130 count. I don't know the significance of the screen color. It was stated in the tutorial that screen sizes between 110-195 could be used but that 137 was perfect. Where did you find 137? Is a variance of 10 significant? Would we than be using a different grade of frit or would it still be powder?

Thank you so much. For those of us in the boonies, this type of education is a true gift.

-Cary

Hi Cary,
I have minimal experience with powder printing so if anything I say below is incorrect, someone else is welcome to set me straight.

I have only ever seen the yellow mesh screens and don't know what the difference is compared to the white mesh screens. Perhaps the yellow mesh is made of a material that holds up better to the abrasive qualities of the glass powder?

The difference between a 130 and a 137 mesh screen is minimal - maybe 5% difference in resolution. A 130 mesh screen will yield a slightly less detailed image, and you should be able to use the same powder used for a 137 mesh. However, if you want to purchase a 137 mesh screen anyway, you can find them at http://http://www.midwestsign.com/index.asp.

Hope this helps.
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Re: Powder Printing

Postby Chris_Petrauskas » Mon Aug 05, 2013 3:43 pm

Hi Cary,

My apologies for missing this post, I'll have to ask around and see if I can find someone that knows anything about this Forum. ;>

So, to break it down, you have two questions here:

• Why yellow vs. white mesh?
• Is 130 mesh OK vs. 137 for powder printing?

Let me start out by saying that you will be perfectly fine using a 130 mesh, white screen so you can relax and keep rolling.

That said, let's take a look at why we choose the 137/yellow as optimal.

Yellow vs. white mesh:

The issue here is not about the mechanical properties of the mesh but how it handles exposure to ultraviolet light to set your image in emulsion.

A white mesh (clear filaments) can conduct full spectrum light so it will tend to pipe UV light beyond the edges of the open areas in your film when on the exposure table and thereby set a slightly larger area of emulsion than you intended.
Yellow mesh, by virtue of its color, filters out UV light so it should expose a more accurate stencil. There is not a huge difference but every cumulative thing you can do to enhance accuracy helps.

130 vs. 137:

@jdepaula is right-on here in that it will yield a slightly lower resolution image. Please be sure to adjust your halftone lpi to support this lower res.

From the lesson you'll remember:
Maximum LPI = 1/4 screen mesh TPI

So, for a 130 mesh screen your maximum LPI will be 32.5 vs. 34.25 for 137 mesh.

The other item to be aware of with a more coarse mesh is that it will deliver the powder at a faster rate and allow some larger particles to get through. Again, not a bad thing per se but it is different from what we demonstrate in the lesson.

Also as @jdepaula mentioned, Midwest is a great dealer if you do want to track down the 137 mesh yellow screens.

http://www.midwestsign.com/

Thanks!

Chris
Chris Petrauskas
Bullseye Glass Co.
Portland, Oregon, USA
http://www.bullseyeglass.com
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Re: Powder Printing

Postby towdesign » Wed Mar 26, 2014 4:55 pm

I'm not ready to make the photo emulsion process but I have some large Katagami stencils. And I thought that if I could just get the right screen to evenly distribute the powder over the stencil my finished product would look better. I'm looking at https://estore.midwestsign.com/storefrontCommerce/itemDetail.do?itm_id=24284&itm_index=0&orderQty=1&cust_item=SFR2024137Y&whs_id=6&orderUom=#

because I'm not ordering in wholesale quantities and I would just want one - is this the right thing I would be looking for? Or Since I'm in San Francisco would there be a place I could just buy the right screen by the yard and make my own frame?


Thanks,
Terry Ow-Wing
http://www.glassart.weebly.com
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Re: Powder Printing

Postby Chris_Petrauskas » Thu Mar 27, 2014 8:59 am

Terry,

That's exactly the right product.

I would strongly recommend against buying raw screen fabric and trying to stretch your own. It really takes specialized equipment and is a bit of a pain to do well let alone the fact that you'd most likely not be able to buy the materials for the cost of a factory tensioned screen.

I should mention that our instructors are testing some of the modular screen systems that allow you to buy a frame and then replace the screen meshes as they wear out using a special tool. It seems to create a good tension and is price competitive with traditional professional replacement. As they are still in the process of testing I can't make a definite recommendation yet but we'll say more as that process concludes.

If you wanted to walk-in to a local store I can suggest Anthem Screen on Geary Blvd.:
http://www.anthemprintingsf.com/

We've bought some supplies from them and they sell quality materials. The only caveat would be that according to their web site they don't specifically stock 137 mesh screens but you could ask them. As I said above there is a fair amount of leeway in the process and you could be successful with higher and lower density meshes but our teachers have found that 137 strikes a good balance between speed, resolution, and use of material. My instinct would to be to err on the side of a higher mesh count. The deposit of material would go more slowly and you'd get less yield of the particles that would fit through but it would be very controlled and precise. A 110 mesh might be a little too loosey-goosey with how fast powder would flow.

The bottom line is to not get to hung up on the screen and just give it a try. Don't make finding the perfect screen the enemy of getting out there and making art. You'll need to adjust and evolve the process to your own taste and style regardless of where you start so I say just grab the easiest to find 137(-ish) screen and have fun! Just be sure to record your set-up and working notes in detail so you know how to adjust going forward.

Thanks,
Chris
Chris Petrauskas
Bullseye Glass Co.
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http://www.bullseyeglass.com
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Re: Powder Printing

Postby haleyeb » Thu Apr 10, 2014 10:18 am

Hi Chris
I have a 120T screen mesh which was a disaster to use with enamel as I think it was too fine… (you do better when you know better.. ;-))
I have some very detailed graphics which I am putting together and am wondering what mesh size to use.. please see attached picture. Based on the BE video am I right in thinking, using 195 I would lose some detail.. perhaps 137 or my 120 current screen? Or would this much detail just be too fine for attempting powder printing??
and of course I will try it out but just wanted some professional advice first… :-)

Thanks in advance.
Haley

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Re: Powder Printing

Postby Chris_Petrauskas » Thu Apr 10, 2014 12:35 pm

Hello Haley,

When you say that printing with the 120 mesh "was a disaster", what do you mean specifically? Do you have pictures of what happened?

I also want to make sure we're on the same track here referring to mesh:
The higher the mesh number, the finer the mesh and therefore the slower the flow of powder through the mesh (and vice-versa). So a 120 mesh is actually more coarse than the 137 mesh that we demo in the lesson. The effect should be that the powder flows a little more quickly and that a greater percentage of the powder particles will be used. And, to a certain degree the resolution will be somewhat lower. Conversely a 195 mesh will be tighter, allowing only the finest of the powder particles through and technically it can support a higher resolution if you prepare your art correctly before burning the stencil.

Please note that per chapter three in the Powder Printing video lesson, our instructors find that anything within the range of 110 to 195 mesh to works well for powder printing.

I can't tell the scale of the image you attached but assuming it is roughly letter size it seems to be within the tolerances you can expect for powder printing. Certainly the black on the left side. Building in the spot colors on the right would be a little trickier. You would have to test as to whether tack firing between colors is required.

About image prep: Is this art in a vector format (such as Adobe Illustrator or .eps) or is it raster/pixel (Adobe Photoshop). Having vector art menas that regardless of how large/small you want to print the edges will always be crisp. If you go back to our two part lesson on Screen Printing Basics you find good info on image prep. There is some wacky math to deal with but getting your input/out resolution dialed when you're preparing your stencil is well worth it.

Thanks,
Chris
Chris Petrauskas
Bullseye Glass Co.
Portland, Oregon, USA
http://www.bullseyeglass.com
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Re: Powder Printing

Postby haleyeb » Fri Apr 11, 2014 6:04 am

Hi Chris
Thanks for the response.
My 120 screen was a disaster when I used enamel. When I swiped through the enamel I could not get the whole image transferred onto the glass… it was bitty, with parts missing. The image shown is the best I could get. I'm sure it was user error.. re: not an even pressure across the mesh but I gave up in the end after trying several times. I was using a wooden squeegee handle with a hard blade which was recommended for a mesh count of 120-200.

The original image shown in my 1st message is Adobe Illustrator and I should have stated that it is zoomed in. I'm using .ai in order to get as you described a sharp clean edge, and I'm just playing about with what I can produce at the moment, and that does not include the spot colours for the moment… It's all I can do to get one colour right for now… ;-)

Thank you for the explanation of the mesh sizes. That's given me a clearer understanding of what to expect. I will experiment and see how I get on with 120 and powder but 195 sounds like a better option for what I am trying to achieve.
Much appreciated for your input :-)
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Re: Powder Printing

Postby suds » Tue Apr 15, 2014 4:06 pm

I've been looking forward to trying this technique for a while.
Yesterday my friendly UPS driver brought me a shiny new 137 mesh screen, and for fun I tossed a spoonful of powder (0008) on the screen and tried to "squeegee" it through the mesh.
Much to my dismay I could only get maybe 1/2 the powder to go through the screen even after dozens of passes with the cardboard squeegee.
Much of the powder is simply too large to go through a 137 mesh screen.

Is this normal for that screen mesh?

Now I wish I'd ordered a 110 instead. :(
Steve
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