# Exposure test with the Stouffer Scale? Lawson SBQ 510?



## camscam (Apr 1, 2007)

Hey I guess this is a 2 part question actualy. I just got my shipment of Lawson SBQ 510 that they say is basicly Ulano QX1, which I know a lot of the guys on here really like from other posts. I was wondering if anyone else has tried it but more importantly, since I havent worked with it before I wanted to do a real good exposure test. I personaly like to expose screens in direct sunlight one, cause its free and two its bright and has lots of UV so I can expose it fast. Getting to the point here I've got a 21 step wedge stouffer strip that aparently can be used to test exposeure times with screenprinting (I've used it in the past with a CtP platesetter). I just havent found any clear instructions or anything that says how to convert the data. For example, IF I expose the scale for 2 minets and the 6 washes out almost and the 7 is "scratchy" what does that calculate out to for correct exposure time? This example is totally hypothetical because my screen is curing right now and I want to do this tomorow, but thats how it would work as far as I know.
I would like any help you guys can give for either doing an exposure test, using a stouffer scale or any tips or comments about exposure with Ulano QX-1 / Lawson SBQ 510. You guys are great and for us noobs its a life saver. thanx in advance. I'll answer any questions in case I was not clear in my descriptions about anything here.

UPDATE: I did a test exposure today in direct afternoon sunlight. I layered the transparency with a design and the Stouffer strip under a piece of clear plexi and exposed for approx. 2.30 minuets. The emulsion did not appear to change color and did not show a "ghost image" of the design. I began spraying and the image started to appear, after about a minuet of spraying lightly with tepid water. However the screen did not clear properly. The unexposed area became skin-like and started tp break up and clear in those areas but it was not a crisp image by any means. It did not fully clear and seemed as though it was overexposed however when I turned the screen around to the underside, all that emulsion had become soft and wet and washed away to a high amount. So it was like the top was overexposed and the bottom was underexposed. how could that happen? Is there anything I can do to prevent this? is it because it was too hot out side? This was considerably different then the speedball diazo I've been experimenting with to date.
I really hope I can get help here. I've been trying to read about exposure tests online and I think the light source may have been too bright? How well does a "party" style blacklight work?


----------



## RichardGreaves (Nov 7, 2006)

Lawson says that Lawson SBQ-510 is similar to Ulano QX-1.

The target for stencil hardness is a solid step 7. If the 7 step is 
"scratchy" (what ever that is), perhaps it is not a solid step 7. If step 7 holds up and stays in the screen, that is your measure of durability. If you want more exposure, you would are more UV exposure until you got a solid step 8. This is my favorite exposure hardness test and it is very repeatable.

Adding a positive of various, measured fine lines will tell you when you light scatter from exposure is undercutting fine lines - which is different from exposure for durability.

Plexiglass will filter more UV light than plate glass.

Because it it NOT sensitized with diazo (yellow), there is little or no color change when it is exposed.

It is an easy rule: If the emulsion washes out - it wasn't exposed. If it doesn't wash out, it was exposed somehow.

For your next exposure, tape a dime to the stencil to see if the dark areas of your positive are failing you and letting UV-A light through to the stencil. If the area covered by the dime doesn't wash out, you have exposed the stencil to UV energy or heat energy and the stencil is resisting dissolving with water and going down the drain.

We often get calls from people that wash outside or actually apply the positive outside, and aren't thinking about the sun.

You didn't describe your positive, so it could be blocking light, you would also see a different effect on the inside of the screen where there was no stencil.

You need to do a standard step exposure test to determine how long you have to expose to get the UV energy to penetrate to the back of the stencil. It doesn't make sense that the sun didn't penetrate to the back of the screen, but the proof is on your fingers.

"party" style blacklights are probably low energy fluorescent lamps that output some range of UV light. They will be much weaker than the sun in UV energy.


----------



## camscam (Apr 1, 2007)

Thanx for attempting to respond to my post, however I think my message was confusing to you and I apologize for not being clearer. I was using the step-wedge scenario as an example of the type of information I was hoping to find and I just made the numbers up about the "scratchy 7".

As of right now I totally ditched the sun as my exposure unit and I've been trying to get the right exposure using the "light bulb over the screen" method with a 150 watt incandescent bulb in a clamp-light reflector, placed about 2 feet over the screen. 
So far I have done 2 timed exposures and both times the screens completely washed out, telling me they are underexposed, I get that part. What I don't know is what would be enough exposure. I did timed exposures first with 45 second intervals, moving a piece of cardboard along the screen as I exposed, like we would do in my photography class.

The first exposure was in 45 second increments, 6 sections of the screen so that most exposed part was exposed for about 4 minuets and washed out.

The second time I tried flashing the whole screen for 2 minuets then did one minuet increments across 5 sections of the screen giving the highest exposure time of 7 minuets. Still the whole thing washed out completely
with almost no effort or need to use the stencil remover so it was very soft indeed.

The times I was basing on come from the Ulano QX-1 spec sheet that lists "method 1" which is a thin coat of emulsion on both sides, as needing 81 seconds of exposure from a 40 watt flourecent tube. so I would think 7 minets would be enough right? Should I try using a compact flourecent light like the ones that fit in a regular light-socket to get more UV light or is the problem just that I'm lacking realistic time specs for using a 150 watt incandescent with photo polymer for exposure?

Hopefully I was clearer this time. I have another screen drying right now and I'd hate to screw this one up after the last two.


----------



## RichardGreaves (Nov 7, 2006)

Jay,

David Landesman (President of Lawson Screen & Digital Products) told me you had written him about your sun experiments. He told me he sent you come links to trouble shooting pages and told you to call me!

Those links are probably the Ulano troubleshooting pages, re-formatted with Ulano permission he has on the Lawson web site.

I posted about sun exposure in this forum:
http://www.t-shirtforums.com/screen-printing/t19817.html#post121127




camscam said:


> I've been trying to get the right exposure using the "light bulb over the screen" method with a 150 watt incandescent bulb in a clamp-light reflector, placed about 2 feet over the screen.


There is no reason to believe that an incandescent bulb would output any UV-A energy, so don't spend too much time on that experiment.

If you are using QX-1, I suggest a more sensitive emulsion like QTX, because you have a reallllllllly low energy UV-A light source. You are better off with the sun and a 21 step gray scale because every 15 minutes the UV-A energy from the sun is different AND clouds get in the way. UV-A is 350 - 420 nanometers, invisible to humans.

There is no correlation for the 40 watt Black Light fluorescent lamp and your 150 watt incandescent bulb.

Search this forum for lots of entries on consumer halogen lamps. They are not designed for screen making. They go to a very high temperature when lit, to vaporize the tungsten that has evaporated off the filament and re-deposited it on the filament because of the halogen gas in the lamp.

These lamps give off LOTS of visible light and some UV-A light. There is usually safety glass to protect your eyes. Remove it and you will let the UV-A light through, but be very careful of the heat, because it could cause fire of burns.


----------



## camscam (Apr 1, 2007)

Richard, Thanx for your help through this. Now, I know why I was still waiting for that response e-mail from Lawson! If they say they tried sending it, I believe they tried, since the president told you he had, but something must have happened because It never came through to me. I got invoice messages when I ordered, but I may have typed the wrong email address in when I did the "ask a question" form. Thats the only think I can think of.

Well you've given me food for thought thats for sure. So it really seems like I've been really barking up the wrong tree with the incandescent bulb. Since the photopolymer is only responsive in the UV-A band of the spectrum. From what I gather you're saying The Sun is a high output UV-A device but the exposures will be all over th place considering the wide shifts in UV-A amounts depending on time of day and weather. And others have had success with this type of polymer using halogen shop lights?
I have Halogen shop lights I use in photography as "studio lights" I can do some test exposures with. And I'll search the forums as well for tips on that. 
But I'm thinking there is probably something better that doesn't generate as much heat and light that is focused more on the UV-A spectrum? They are probably expensive though right?

As far as what I've been doing to test the exposure - supposing the light was the right kind - does it seem I've done the steps right? What about the *Stouffer Scale? is there a reading I should see with a properly exposed stencil?

Thanx again for your help.
*


----------



## RichardGreaves (Nov 7, 2006)

camscam said:


> What about the *Stouffer Scale? is there a reading I should see with a properly exposed stencil?*


Click on link I posted. What more do you want?

Studio lights are tuned for photographic VISIBLE LIGHT FILM, not invisible UV-A sensitive screen stencils, but you are not using photographic lights, but shop lights. Perhaps there may be some UV-A in a photo lamp, but that is not it's purpose so you have to make the experiments I suggested.

Don't waste your time with what you happen to have in your studio. If you studied photography, you understand that camera film and digital camera chip respond to different light energy differently. Daylight film doesn't work well with fluorescent light.

Focus on UV-A if you are building your own equipment

As far as cost, only you can determine what you want to spend. If you farm the work out to someone else, you can focus on selling designs, not printing. 

There is more money in selling shirts than printing shirts, especially if you don't know how to print shirts.


----------



## camscam (Apr 1, 2007)

I think thats the phase I'm at then, I need to DIY-up an exposure device that uses high UV-A output lights and check exposure accuracy with the stofer scale getting a solid 7. In the mean time I guess will go back to sunlight exposures to see what I can get.


----------



## camscam (Apr 1, 2007)

UPDATE:
I have been trying to get a proper exposure this whole time still with no luck. I wrote Lawson again and told them I had problems and needed advice but didn't get a reply - again. SO I gave them a call and the guy I was explaining the problem to was going on and on about how I had not bought high-end emulsion and that Lawson 510 is for use with high UV output commercial exposure units and I should not and could not expect it to work otherwise, when I tried to slow him down to discuss the possibility that I bought the wrong product for my needs, he hung up on me! I called back and spoke with a calmer guy who said virtually the same thing however. I explained to them that when doing sun exposures the front set up like a skin that peeled off and the back washed away but rather then address the actual issue they wanted to shift the conversation to promote the screen printing classes they conduct for a fee of course. I just want to return the unused portion of the product at this point because the product description in no way represents the reality. I left a voice message for the owner to that affect and I hope that this can be resolved reasonably. I can't believe that things went down like this. I called for help and got every reason in the book about why they couldn't help me. Why would I want a 20 dollar bucket of useless goo? If this needs special considerations to work they need to put it on the web page so only the people that can use it will buy.


----------



## Solmu (Aug 15, 2005)

Caveat emptor. *Every* product should only be bought by those who can use it. When you're buying professional products from professional companies, you can't ever assume that they will work with amateur methods. If they do it's a bonus.


----------



## camscam (Apr 1, 2007)

Solmu said:


> Caveat emptor.


I guess I need to brush up on my Latin. So thats translates into "You're Sht-Fked!"? All it had to say was "for use with commercial exposure devices" or something to that affect and I wouldn't have bought it. I believe that an online store has the same responsibility for selling a product as a walk-in store but maybe I'm old fashioned. 



> "*Every* product should only be bought by those who can use it.


I hear ya man- and its like, how the hell would I know before I tried using it?? I guess its true and I should stop buying those "Magnum" size condoms too...

But seriously, I figured the diazo I bought from speedball says "such and such exposure method" and the website this product is sold on calls it "a fast exposing emulsion that is easy to use" with no mention of equipment requirements, lights, spectrum of light it's activated by or recommendations AT ALL of ANY kind EVER. Is it a stretch to assume it would be at least similar to the other emulsion?

I think the product description is a misrepresentation of the product or in the very least an over site. I don't believe they would assume that they only get commercial accounts as buyers. Anybody in the world can buy online and people depend the information they have available to make a decision. I didn't even know the company's stand on the product/results until I called yesterday - The thing that really upset me was they didn't give me ANY useful info just said I couldn't use it. So I have to buy a $500.00 exposure table to work with my 20 dollar emulsion? So much for customer service.

A full 2 weeks of dicking around with it, thinking "trial and error comes with the project" and trying to stay motivated - with no help from the manufacturer (even after multiple requests), let alone a spec-sheet or anything in the line of instructions or recommendations. I'm supposed to pull the information out of my arse?? I may sound mad and at this point I am. They'd better let me return it for store credit or something else cause this is BS. Just time and money down the drain, with a blue-green color to it.

I'm going to try this 500 watt halogen I bought today for one more test...


----------



## Solmu (Aug 15, 2005)

camscam said:


> I guess I need to brush up on my Latin. So thats translates into "You're Sht-Fked!"?


Essentially 



camscam said:


> All it had to say was "for use with commercial exposure devices" or something to that affect and I wouldn't have bought it.


I agree that that would have been nice/useful, and not a big deal for them to do. But at the same time, Lawson don't make products for hobbyists. Speedball on the other hand don't make products for professionals. There's overlap (a hobbyist can use Lawson and a professional can use Speedball) but they have different target markets.



camscam said:


> The thing that really upset me was they didn't give me ANY useful info just said I couldn't use it.


Yeah, that did sound really rough - especially hanging up on you.


----------



## camscam (Apr 1, 2007)

I left a message for the owner of the company who will be "back in town Monday" according to the staff, so I can't completely condemn them until I talk to him provided he calls. Tomorrow I'm testing with a halogen so maybe there is hope.


----------



## RichardGreaves (Nov 7, 2006)

camscam said:


> I wrote Lawson again and told them I had problems and needed advice but didn't get a reply - again.
> 
> SO I gave them a call and the guy I was explaining the problem to was going on and on about how I had not bought *high-end emulsion* and that Lawson 510 is for use with *high UV output commercial exposure units* and I should not and could not expect it to work otherwise, when I tried to slow him down to discuss the possibility that I bought the wrong product for my needs, he hung up on me! I called back and spoke with a calmer guy who said virtually the same thing however.


Writing is unreliable if you want immediate results. (I haven't looked at my eMail for four days while I was at the Printwear Show in Baltimore.)

Who told you, you bought the wrong emulsion? If you don't have a name of the person, nobody can get you any satisfaction. 

You bought an SBQ emulsion that has very good resolution, but not as much speed as their own SBQ 500 or Ulano QTX. You got resolution, not speed.

Lawson SBQ 510 *does NOT* require "high UV output commercial exposure units", and you can tell anybody that Richard Greaves said so. The sun has plenty of power and certainly more than an Expo-Light.

Now, you do have to do a 'dime' test, or any class of an exposure test to know what your exposure time is.

If you suspect that the SBQ 510 is no good, you can prove that in 10 minutes. Put a 2" coat of emulsion on a screen, dry it and take it outside. Put a coin on it every 30 seconds until you get bored. Wash it out and you will know if the emulsion is working. You will know how long an exposure it takes to harden the stencil so it doesn't wash out.

Bill Hood's $9.95 lesson teaches you to how to print a test positive and how to make a step test.

Buy a Stouffer 21 step gray scale for repeatable monitoring of every exposure you make. Aim for Step 7. 8 means more than you need, 6 means you need more.




camscam said:


> I explained to them that when doing sun exposures the front set up like a skin that peeled off and the back washed away but rather then address the actual issue they wanted to shift the conversation to promote the screen printing classes they conduct for a fee of course.
> 
> I just want to return the unused portion of the product at this point because the product description in no way represents the reality. I left a voice message for the owner to that affect and I hope that this can be resolved reasonably.
> 
> ...


When you call David when he gets back, I don't know what more he could tell you except to apologize for the poor service you said you got. 

But I do not understand what might be wrong with the description:

_SBQ convienence of presensitized at the factory, but about as fast exposing as Ulano TLX. Easy to remove even if underexposed and used with strong ink and cleaning solvents. Ready to use,no sensitizer to add so it doesn't go bad for 12 months. Medium-speed exposing SBQ photopolymer direct emulsion for industrial and fine halftone graphics printing with conventional or waterbased UV & solvent based inks. Its matte finish virtually eliminates printing problems associated with high and low humidity. 37% solids - Presensitized, and breakthrough price. 1 year self life.

Quantity Discounts Call Today 
Pre-sensitized at the factory - No Mixing - Ready to coat. 
About half the speed of SBQ QTX


_You will have little luck returning unused portions of emulsion unless you demonstrate the product doesn't work. If the emulsion proves to be bad and doesn't crosslink, (which would be ultra-rare, because SBQ 510 is pre-sensitized at the factory and tested before release), Lawson will replace it.

Because of your inexperience, (and now your experience), you know that you can buy an emulsion that exposes twice as fast. 

If "_the front set up like a skin that peeled off and the back washed away_", you didn't expose your stencil to the sun for long enough. If areas that were exposed wash away, there is not enough exposure to crosslink the sensitizer.


----------



## camscam (Apr 1, 2007)

Richard, you are the man.


> Who told you, you bought the wrong emulsion? If you don't have a name of the person, nobody can get you any satisfaction.


I have the names of the guys I talked to. GARY is the one who hung up on me after saying that I should have bought higher quality emulsion, the 510 is for use with hight UV output commercial exposure devices and that I was "bush league" and no one would want to help me because I was not using commercial equipment. The other guy Andy I think was the one who said roughly the same but in a nicer way and then "had to take another call" and gave me David's voicemail.



> f you suspect that the SBQ 510 is no good, you can prove that in 10 minutes...You will have little luck returning unused portions of emulsion unless you demonstrate the product doesn't work.


I know it "works" in thats its sensitive to the light so I think you are right that trying to get a refund will be fruitless. I actually think I've got it now with the 500 watt halogen I just bought. I exposed a portion for 25 min. that had the stouffer strip on it and got a solid 6 so it was a little under exposed, but the test image/stencil looked great when it washed out and detailed portions and fine lines washed out this time and the rest stayed, so the advice from yourself and the forum members has helped out a lot.

I see now that my prior tests with 150 watt light sources in the 10 min range were never going to work, but that's exactly why I was calling Lawson directly, to find out "minimum requirements" for light source and exposure time with different sources of light. What I didn't want was every excuse in the book for why it wasn't working- I could TELL it wasn't working! I also didnt need them to try to sell me "something else" like classes, exposure tables or higher-priced emulsions. I think both of these guys are in sales, not service and rather then just tell me they were unfamiliar with the product looked at it as a "lead" to sell more.The last thing a customer that just bought something from a company and is having trouble with it is going to do is to buy anything else from that company until they get the first thing they bought to work!

So the good news is I think this WILL work. And now I can move on to the next phase of "trial and error" with printing. 

I like that this is considered a high res emulsion because I like detailed graphics. Time for exposure is a bit long but at least it works and I'm not in a rush or anything so it's perfect for my needs as long as it makes a good screen and prints in the end.

My motivation is not to badmouth this company or product, just to figure it all out and I will talk to David seriously about the tech support and customer service issues I experienced, which I understand are wholly unrelated to the quality of the product being vended.

I FINALLY GOT A USABLE STENCIL!!! I'm freaking happy!

UPDATE:
I talked to David, president of Lawson on the phone just now and he was nice, and understanding of my "doin' it at home" scenario and all. He assured me that he had responded to the email requests for support I sent and they were returned. I gave him a different one to try so finally I will be getting those tips. Also "Gary", is going to get a talking to for being a dick. This emulsion is formulated for wide exposure latitude and detail. It is NOT the case that this emulsion needs any commercial equipment to make a well-imaged screen. If anyone else is using this product with a "single point light source" halogen I will give you info on my setup because it seems to be working out fine.


----------



## ratdaddy (Sep 25, 2009)

I'll tell you from personal experience. Lawsons is a great company to work with if you are using Lawsons supplies AND Lawsons equipment.
If you bought their emulsion and are NOT using one of their exposure units, your not going to get much help. Also I would be tempted to say that since you opened and used a portion of the emulsion they are not going to take back the remainder. Simply because they do not know where you opened it or how it was handled once it was opened.

After reading your posts every time you stated that it washed out completely. This tells me you never fully exposed the screen.

I have a homemade exposure unit. It consists of 5-24" Flourescent "Grow" lights used for plants, in a wooden box approximately 8 inches deep. it is covered with a piece of tempered glass. The inside of the box is painted white and the lights are evenly spaced parallel across the box. I place my screen and art face down on it and I have a piece of foam that is cut to fit snug inside my screen. Then cover it with a piece of black poster board. I expose for 4 minutes and it works perfectly. I use Lawsons SBQ510 presensitized and I have never had any problems with it. I have accidently run overontimeand it still worked great. +or- 30 seconds.


----------

