mor

hello everyone!

first of all, pardon my english, i am not from the states.

my emulsion was in the refrigirator for about a year so when i wanted (finally) to cover a screen with it she was very lumpy so it came out to be very thick layer of emulsion on the screen.

i exposed it to an 500W helogen lamp for 6 minutes. i washed it and at first the picture started to wash out (and i was very happy - this is my first time) but then all the emulsion washed out, including the parts i exposed.

so what could it be? the exposing time? the thick layer of emulsion? or maybe the emulsion it self?

can i dilute the emulosion or do i have to buy a new one (i used it only once )

thank u...

oh yea one more thing... do you know an online store for screen print supplies that ships her goods to israel?

 

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splathead

your emulsion may be too old. It does have a shelve life depending on your brand. Generally 3 months.

Also depending on your brand, 6 minutes may be too little time. Have you successfully exposed screens with this time and emulsion before? My emulsion requires an exposure of 13 minutes with a 500 halogen.

 

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Dad

I agree I don't think you exposed them long enough. A exposure calculator is worth it's weight in gold.

Dad

 

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kbdmarketing

Old emulsion most likely, then cold would increase viscosity. The lumps sound as if it's past its shelf life.

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SendATee.co.nz

Tend to agree with the above, a number of factors could be the cause of the wash out.

Did you degrease the screen first?- Was the screen 100 % dry before applying the emulsion?
Was the emulsion totally dry before you shot the screen? thick or thin I'd say it needed more time over your light ( Splathead ) . Also when your washing out don't blast the screen with full pressure. i generally use very low water pressure until the whole image is clear & then give a very "short" burst on high.

I have used some 12 month old emulsion in desperation on a couple of occasions but to be honest it's probably one of the main reasons it fell off you screen.

good luck.

 

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mtmob

Quote: Originally Posted by mor hello everyone! first of all, pardon my english, i am not from the states. my emulsion was in the refrigirator for about a year so when i wanted (finally) to cover a screen with it she was very lumpy so it came out to be very thick layer of emulsion on the screen. i exposed it to an 500W helogen lamp for 6 minutes. i washed it and at first the picture started to wash out (and i was very happy - this is my first time) but then all the emulsion washed out, including the parts i exposed. so what could it be? the exposing time? the thick layer of emulsion? or maybe the emulsion it self? can i dilute the emulosion or do i have to buy a new one (i used it only once ) thank u... oh yea one more thing... do you know an online store for screen print supplies that ships her goods to israel?

Yeah i think everyone is right the shelf life is a big factor.

also when you expose yur screen with a hologen lamp like i used too try putting the light about 15 inches above the image then leave expose for 15 minutes i never had a problem with exposing this way....so good luck.

 

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mor

thank u all for answering

 

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RichardGreaves

Quote: Originally Posted by mor my emulsion was in the refrigirator for about a year so when i wanted (finally) to cover a screen with it she was very lumpy so it came out to be very thick layer of emulsion on the screen.

When emulsion manufacturers tell people not to let the photo sensitive emulsion get warmer than skin temperature, (like photo film and children, should not be locked in the car trunk), most people think of the refrigerator. The refrigerator is 40°F which is 10°F from ice cream, and just as bad.

The protection doesn't come from the cold, but keeping the emulsion below skin temperature.

You forgot to tell us what your emulsion is.

Diazo sensitizer reacts with water and when you mix it into the emulsion and it slowly goes bad in 4 to 6 weeks like milk and lettuce.

SBQ emulsion is presensitized at the factory, doesn't use diazo and has a shelf life of 12 to 18 months.

Lumps in any emulsion usually means heat damage and there is no fixing it. Use it for blockout.

Beware of coating refrigerated emulsion because it gets thicker. You will coat more than you know, and it might drip as it warms up.

Quote: Originally Posted by mor i exposed it to an 500W helogen lamp for 6 minutes. i washed it and at first the picture started to wash out (and i was very happy - this is my first time) but then all the emulsion washed out, including the parts i exposed.

The stencil "could" still "work" with more exposure. Emulsion will dissolve and rinse down the drain if you don't expose it long enough for the sensitizer to cross link the polymers.

For more information on using a 21 Step Transmission Gray Scale to measure exposure, please read the post I made this morning and search forum for "exposure test" and "21 step". I have made hundreds of posts explaining this.
Exposure FAQ of Screen Making Products

Quote: Originally Posted by mor do you know an online store for screen print supplies that ships her goods to israel?

This is a serious supplier in Tel Aviv:

ARTA ART GRAPHICS & OFFICE SUPPLIES
83 Nachalat Binyamin Street
Post Office Box 606
Tel Aviv IL-61006
P: +972-3 560 1921
F: +972-3 560 9722
ARTA

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lunarc

I currently use the 500watt halogen bulb as well, i have it 16" above and expose for 12:30 seconds. Designs come out solid...but I agree with the others about the old emulsion being the first problem

 

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