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coating help needed

Posted: Wed Jul 11, 2018 2:11 pm
by ahgu
I don't know how Rallisson did his pin coating. I cannot get uniform coating with DCG. See picture below.

solution about 5-25-120. Temp 40-50C. veil coat it first then spin at 80RPM Under regular light, it is very obvious it is not even.

coating2.jpg
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I also tried mold coating. Looks good until developing, Get those circular flow pattern left after developing. Shim is about 50um. Final dried thickness about 7-8um thick.
coating3.jpg
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Also tried Meyer bar, first try left thread mark, heat it up, no more thread mark, but uneven.

DCG solution is pretty thick even at 50C, it is very resistant to flow. I wonder how you guys get it to flow uniformly.

Re: coating help needed

Posted: Wed Jul 11, 2018 2:17 pm
by ahgu
The white is another issue. I suspect the cause was
1. the solution was not overnighted.
2. Did not wash out all the D after fixer.

I suspect 1 might be main cause. The gelatin needs time to form better bonds. Correct me if wrong.

Re: coating help needed

Posted: Thu Jul 12, 2018 7:00 am
by holomaker
When mold coating do not force dry it at all, otherwise
You may be sealing in moisture, don’t heat plates prior
To coating more than “just warm”, what thickness
Shim are u using , possibly films to thick to harden through out causing milky....

Re: coating help needed

Posted: Thu Jul 12, 2018 11:22 am
by ahgu
Shim is about 50um. Final dried thickness about 7-8um thick.

What is the cause of the whiteness after developing? I don't get this with high bloom GEL , but get it with this type of 214 , 29.6mp viscosity, 5.3ph gelatin.

Re: coating help needed

Posted: Sun Jul 15, 2018 10:10 am
by ahgu
http://www.holographyforum.org/data/pdf ... tation.pdf

Anyone how the idea behind this coater?
coat.PNG
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Re: coating help needed

Posted: Mon Jul 16, 2018 9:53 pm
by Steven
ahgu wrote: Sun Jul 15, 2018 10:10 am Anyone how the idea behind this coater?
coat.PNG
Hi ahgu, I suspect that it is using a Doctor Blade. Something like this:
https://www.youtube.com/watch?v=f0OfjqKQwXg

Steven.

Re: coating help needed

Posted: Tue Jul 17, 2018 3:24 am
by Martin
Steven wrote: Mon Jul 16, 2018 9:53 pm
ahgu wrote: Sun Jul 15, 2018 10:10 am Anyone how the idea behind this coater?
coat.PNG
Hi ahgu, I suspect that it is using a Doctor Blade. Something like this:
https://www.youtube.com/watch?v=f0OfjqKQwXg

Steven.
I think it's based on some kind of curtain coating (http://holotec.de/Produkte_und_Dienstle ... index2.htm).

Re: coating help needed

Posted: Tue Jul 17, 2018 7:01 am
by Steven

I think it's based on some kind of curtain coating (http://holotec.de/Produkte_und_Dienstle ... index2.htm).
I think you must be right. Film thickness is dependant on coating speed.

Re: coating help needed

Posted: Sun Jul 22, 2018 11:06 am
by ahgu
Martin wrote: Tue Jul 17, 2018 3:24 am
Steven wrote: Mon Jul 16, 2018 9:53 pm
ahgu wrote: Sun Jul 15, 2018 10:10 am Anyone how the idea behind this coater?
coat.PNG
Hi ahgu, I suspect that it is using a Doctor Blade. Something like this:
https://www.youtube.com/watch?v=f0OfjqKQwXg

Steven.
I think it's based on some kind of curtain coating (http://holotec.de/Produkte_und_Dienstle ... index2.htm).
Curtain coating requires gravity. This equipment is on a flat glass bed. I suspect it is some sort of blade.

Re: coating help needed

Posted: Wed Oct 10, 2018 6:18 am
by holomaker
Spin coating needs a larger plate than you are using , 80rpm is not enough, either spin larger plates or spin the tiny plate faster !