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screen printing => Equipment => DIY - From master engineered marvels to cobbled together jury-rigged or Jerry-built junk! => Topic started by: JonnyP on October 16, 2019, 06:10:57 PM

Title: Will a standard Stouffer 21 Step Sensitivity Guide work for UV LED system?
Post by: JonnyP on October 16, 2019, 06:10:57 PM

Hi, I'm building a UV LED Exposure Unit, will be using Saati PHU emulsion (I think), and I am trying to calibrate the exposure and see if there are any hot spots on the glass. Wondering if there is any difference among the various exposure guides, and if it matters at all that I'm using UV LED instead of other light sources. Thanks.

Title: Re: Will a standard Stouffer 21 Step Sensitivity Guide work for UV LED system?
Post by: Colin on October 16, 2019, 08:17:51 PM

Light transmission is light transmission.

Using the 21 step calculator will give you your best overall understanding of how solid your emulsion has gotten during your exposure.

You will definitely want to check multiple locations across your screen for proper exposure and "hot or cold" spots.

What is the light source you are getting?  Not all LED's are created equal.....

Title: Re: Will a standard Stouffer 21 Step Sensitivity Guide work for UV LED system?
Post by: Robert Clark on October 17, 2019, 09:40:09 AM

Great advice Colin !  21 step guide should be in every shop to have a better understanding of what is going on with your exposure unit.

Title: Re: Will a standard Stouffer 21 Step Sensitivity Guide work for UV LED system?
Post by: JonnyP on October 22, 2019, 02:54:01 PM

Hi, thanks for the responses.
I'm using single point UV LED:   200W UV 395nm~405nm LED Emitter DC30V-36V 6A On Copper PCB, with appropriate driver.

Title: Re: Will a standard Stouffer 21 Step Sensitivity Guide work for UV LED system?
Post by: Colin on October 22, 2019, 06:49:46 PM

You should be fine with that unit.  Its not in the "perfect" wavelength for LED, which is a hard 405nm but you will find success.

What you will find is the emulsion is just a touch "softer" or has more flex than a screen exposed on a hard 405nm or on a Metal Halide.