Mayer bars

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Joe Farina

Mayer bars

Post by Joe Farina » Thu Sep 16, 2010 8:49 pm

There is an interesting chart showing the wire size of Mayer bars vs. the wet thickness of the resulting layer at:

http://www.rdspecialties.com/Page.asp?Script=14

Years ago when I first tried Jeff Blyth's red-sensitive DCG, I thought there was a reference by Jeff or someone else stating that a Number 24 Mayer bar would produce a dry film thickness of around 10 microns. This is the thickness that Jeff specified for his MBDCG layers, but I can't find his specific reference to a number 24 bar. Does anyone remember that? (I think the gelatin percentage in his formula is around 12%.)

Until now, I didn't have a good method to measure layer thickness, so I don't know what my prior coatings were like. I'm guessing that a number 48 bar might give around a 20 micron dry thickness. Probably the best thing to do is make some TMG/MB (and R6G) DCG coatings with my 24 bar, do a series of measurements to get a handle on thickness, then order a larger size (maybe a variety of sizes) from RD Specialties based on those measurements.

JohnFP

Mayer bars

Post by JohnFP » Fri Sep 17, 2010 10:49 am

http://www.holowiki.com/index.php/Myer_Bar_Coating
http://www.webcoatingblog.com/blog/2005 ... coate.html

I have found the 25 and 40 to work well. The 25 seemed to produce close to what the veil spin method did, so I am guessing around 7 - 9um. The 40 worked well too but surely wasthinker. I am guessing about 15 - 18um. This was at 10% gelatin to water.

To save money, you could just buy the 25 and try it, and if you want it thicker, place some tape at the ends to raise the bar up the thickness of the tape. Tape can be found in 1/2 mil for 12.5 additiona um and 1 mil for and additional 25um thickness.

Keep us posted if you get acurate measurements.

dave battin

Mayer bars

Post by dave battin » Fri Sep 17, 2010 11:02 am

JohnFP wrote: To save money, you could just buy the 25 and try it, and if you want it thicker, place some tape at the ends to raise the bar up the thickness of the tape.
would varing the gelatin/water ratio have an influence on the meyer bar's output (as it does in mold coating) ?

JohnFP

Mayer bars

Post by JohnFP » Fri Sep 17, 2010 3:10 pm

Absolutely Dave, but you may not want to change your formula.

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