# Is it possible to completely avoid "sawtooth"?



## MaximRecoil (May 18, 2010)

I see sawtooth even from the pros. For example, this is from Berg Activewear, which is a large, high-production business that has been around for a long time:










To be fair, such prominent sawtooth isn't typical of them, at least not with all ink/shirt color combinations that they do.

You can see sawtooth on this screen from Catspit Productions:

https://youtu.be/rHZ8neUzbJo?t=14m28s

And in this Catspit Productions print:










The Catspit guy uses top-end equipment and he's been screen printing since he was 11 years old.

You can create perfect sawtooth-free edges by not using emulsion at all, but rather, using a hand-, machine-, or die-cut stencil between an open screen and the shirt, but can it be done with emulsion? 

In my case (I'm just a hobbyist using a 500 watt halogen light for exposure), I don't usually get noticeable sawtooth on the printed shirt, but if you look very closely at the screen under good light, you can see slight sawtooth on the curved and angled edges. The cleanest edges I've ever printed were the first screen prints I ever did, using hand-cut paper stencils and an open screen, before trying emulsion. Of course, your design options are very limited with hand-cut stencils.

I'd like to see an extreme closeup picture of an emulsion stencil on a screen that has zero sawtooth, i.e., one that looks like it was carved out by the finger of God. Is such a thing possible, and if so, how is it done?


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## jeron (Jul 16, 2012)

Someone can correct me if I'm wrong, but saw tooth edges are the result of an under cured stencil most of the time. 

The reason it looks like a sawtooth is because the emulsion wasn't strong enough to bridge the mesh opening. So it only sticks to the actual mesh fibers.

But in reality the emulsion should be able to bridge that gap no problem. 

If you have a saw tooth problem it's more then likely a exposure problem. But it could be a film, screen coating, or washout problem too. 

I'll see if i can find a good screen to show that it's possible. If you get all your things dialed in with screen coating, exposure, and washout it is easy to produce nice sharp screen.


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## jeron (Jul 16, 2012)

*Re: Is it possible to completely avoid &quot;sawtooth&quot;?*

Here are some pics of an old screen. I tried to get clear shots. Hopefully you can see everything. This is a 110 screen also.


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## jeron (Jul 16, 2012)

MaximRecoil said:


> The Catspit guy uses top-end equipment and he's been screen printing since he was 11 years old.


Keep in mind just because someone has fancy equipment, and been "in the industry" for a long time, it doesn't mean they know what they are doing. 

I'm saying that as a general term, not directly at the cat spit guy necessarily.


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## splathead (Dec 4, 2005)

First off, you really have to be looking for sawtooth to see it. How magnified are these pictures?

Sawtooth all has to do with the mesh. It is after all an intersecting weave of horizontal and vertical strands creating square space.

If you want to minimize it, use a higher mesh screen and hope your customers don't walk around with a magnifying glass. 

P.S. I'm not convinced that first picture is sawtooth. Rather an intentional design element.


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## jeron (Jul 16, 2012)

I agree to a point, sawtooth will be minimized by using a higher mesh, only because the holes are smaller. 

But you should still be able to produce a screen that is sharp and free from sawtooths on 25 mesh screen.


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## beanie357 (Mar 27, 2011)

Higher mesh, but finding an emulsion that bridges well, and dialing in your burn time will give satisfactory results.
Correct EOM also plays into getting an emuslion to bridge nicely.
We just changed off oraange to get a better bridge.


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## Ripcord (Sep 2, 2006)

Another major cause of sawtooth edges is too thin a coating of emulsion. This will be complicated if you only coat on the shirt side of the mesh, which results in the gasket being on the squeegee side. So when you print the edges take on the definition of the mesh. A thick stencil on the correct side and a properly exposed screen should result in no sawtooth at all. Sometimes a jpeg will also give the illusion of a sawtooth on an edge that's straight.


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## MaximRecoil (May 18, 2010)

*Re: Is it possible to completely avoid &quot;sawtooth&quot;?*



jeron said:


> Here are some pics of an old screen. I tried to get clear shots. Hopefully you can see everything. This is a 110 screen also.


That 3rd picture is excellent; is it through a magnifying glass? Definitely no sawtooth there. You can see the emulsion perfectly bridging the openings in the screen. Can you detail your method, supplies, and equipment?



splathead said:


> First off, you really have to be looking for sawtooth to see it. How magnified are these pictures?
> 
> Sawtooth all has to do with the mesh. It is after all an intersecting weave of horizontal and vertical strands creating square space.
> 
> ...


As I said in my OP, I don't usually get noticeable sawtooth on my prints, though it can be seen in the emulsion stencil if you look close enough. The only time I've gotten noticeable sawtooth in the print was when using a _higher_ mesh count than usual (156 instead of 110), and I suspect that's because there's less ink flowing through. I think that with the increased ink flow of a 110, there is perhaps just enough ink bleed around the edges that, if the sawtooth in the stencil is minor enough, you won't be able to make it out on the print.

The first picture is definitely sawtooth. I'm the one who created the vector file for that print, and I didn't design in any sawtooth. Here's a screenshot of the actual file:










I made that in 2004, and it was my first time ever using a vector program. I had to learn as I went, and I had to draw each one of those letters (they aren't a font). In hindsight, it is terrible (those letters are all out of whack, geometrically and symmetrically speaking), but it is still vector with perfectly straight lines and perfectly round curves. 

I didn't do my first screen print until a little over a year ago. The very first print I did using an emulsion stencil was that design, though I'd created a new vector file in Illustrator, drawing geometrically and symmetrically perfect letters this time, given that I'd been using AI for about 10 years at that point and actually knew what I was doing. I didn't get any significant sawtooth in my prints. Here is the test print I did:












Ripcord said:


> Another major cause of sawtooth edges is too thin a coating of emulsion. This will be complicated if you only coat on the shirt side of the mesh, which results in the gasket being on the squeegee side. So when you print the edges take on the definition of the mesh. A thick stencil on the correct side and a properly exposed screen should result in no sawtooth at all. Sometimes a jpeg will also give the illusion of a sawtooth on an edge that's straight.


My emulsion coating is as thin as possible, but I don't normally get significant sawtooth in the print, at least not with 110 mesh screens. As I said before, I did get a bit of noticeable sawtooth when I used a 156 mesh screen, which you can see here, especially along the bottom and left edge of that "B":










Also, the difference between sawtooth that's in the print, and the inherent stairstepping effect of displaying images on a monitor's pixel grid, is easy to distinguish. For example, that CorelDraw screenshot above shows monitor-induced stairstepping, even though under the hood of the actual vector file the lines and curves are mathematically perfect.


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## PositiveDave (Dec 1, 2008)

I think that they're trying to get a high build on the prints, low mesh count and a bit of saw-toothing. Frankly shirts get viewed from a few paces (unless it's a good friend) so you won't see it.


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## MaximRecoil (May 18, 2010)

PositiveDave said:


> I think that they're trying to get a high build on the prints, low mesh count and a bit of saw-toothing. Frankly shirts get viewed from a few paces (unless it's a good friend) so you won't see it.


Low mesh count doesn't cause sawtooth edges, as demonstrated by Jeron's magnifying glass picture of a sawtooth-free emulsion stencil on a 110 mesh screen. The mesh count affects the specific appearance of the sawtooth edges (more or less prominent) if you already have an underlying sawtooth problem. 

And yes, in many cases, sawtooth edges aren't noticeable at normal viewing distances (although the first picture I posted in my OP is a rather prominent case, and is noticeable even from a few paces), but I'd still prefer no sawtooth at all.

The next time I burn a screen I may try increasing the time from 7 minutes to 8, though I haven't seen any signs of under-exposure at 7 minutes. For example, my screens reclaim easily and don't get slimy when rinsing out the stencil.


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## dvineci (Feb 25, 2011)

It's possible to get 0 sawtooth, but Perfection is in the finish result


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## jeron (Jul 16, 2012)

*Re: Is it possible to completely avoid &quot;sawtooth&quot;?*



MaximRecoil said:


> That 3rd picture is excellent; is it through a magnifying glass? Definitely no sawtooth there. You can see the emulsion perfectly bridging the openings in the screen. Can you detail your method, supplies, and equipment?


Yeah, it is. I use it to look at my film for detail and stuff.

Here it is on amazon. For the price, it is an awesome tool.
High Quality 10X Optical glass Magnifier Lighted Jeweler loupe w/ Measure Scale

I also attached a pic of it sitting on a 20x24 inch screen so you can get an idea of how big it is.


As far as my process. I coat my screens 1/1 using the round side of the scoop coater. I use Saatichem Graphic PHU emulsion. I expose for 7-15 seconds (yes seconds) using a 5000-watt Olec metal halide exposure unit. It also has a vacuum blanket. I then wash out with a standard garden hose and sprayer using the shower setting.


I have a 25 mesh screen that I may try and burn this same image in just to show that mesh count has nothing to do with getting sawtoothing.


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## MaximRecoil (May 18, 2010)

*Re: Is it possible to completely avoid &quot;sawtooth&quot;?*



jeron said:


> As far as my process. I coat my screens 1/1 using the round side of the scoop coater. I use Saatichem Graphic PHU emulsion. I expose for 7-15 seconds (yes seconds) using a 5000-watt Olec metal halide exposure unit. It also has a vacuum blanket. I then wash out with a standard garden hose and sprayer using the shower setting.


Thanks for the information. I wish I had a nice exposure unit like that, but with screen printing only being a hobby for me, I can't justify the expense. 



> I have a 25 mesh screen that I may try and burn this same image in just to show that mesh count has nothing to do with getting sawtoothing.


I'm already convinced, but it would be a good experiment nonetheless, because it seems to be a common belief that mesh count has something to do with sawtoothing.


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## jeron (Jul 16, 2012)

Keep watching your classifieds or Craigslist. That exposure unit and vacuum table is worth thousands of dollars, but i picked both of them up in the same package deal for $350. I realize that is on the extreme side of getting deals, but some good things can be had buying used.


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## depositzim (Mar 16, 2016)

Depending on the mesh used. Could be angle of mesh stretched would you let us know? 

Sent from my D6603 using Tapatalk


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