Preparing photos for Glass Sandblasting/Etching Output

KD
Posted By
Kirk_Dickinson
Aug 30, 2004
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4105
Replies
12
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Closed
A lady in my church cornered me today and heard that I was a photoshop guru. (Which is not true, I don’t even know what I don’t know.)

Now, I know NOTHING about the other end of this except what she explained in 5-min at church.

I guess she used to work in a shop that made all kinds of Glass etchings and she understands the process from printing to making the screens(masks), but not the Photoshop end of it. She says when she has a photoshop file and converts to greyscale and outputs to her printer, then builds the masks, that the results are horrible.

I was immediately thinking that she needed to convert from greyscale to a Bitmap halftone screen. I don’t know what settings to use for her needs, but this looked like a good way to solve her problem. I also thought of the cutline plugin that I have previously read about here. Or maybe even the filter/sketch/halftone filter.

However, I got to searching the internet tonight for glass sandblasting and etching and have found some stuff that is pretty cool that obviously needs more advanced techniques than what I was able to think of.

For instance: <http://anw.com/glass/carved.htm>

There are obviously different levels of "blasting" and some of them appear to be gradients. I can see how different degrees of sandblasting can be achieved by using levels and different masks, but how can a gradient be accomplished?

Can someone either explain how this all works, or point me to a good FAQ? Thanks,

Kirk
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glass output prepare

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P
povimage
Aug 30, 2004
I’d say you’d need to approach it one of two ways, assuming your original is a photo:

1) Posterize the original B&W image to say 3 or 4 levels.

2) Use something like Streamline to turn the photo into paths/shapes, posterizing again to say 3-4 levels..

If you go to say 6-8 levels, you could use half-tones or patterns for some of the "levels" after you’ve posterized..

Of course, it would likely be easiest to start with graphic greyscale vector art in say 3-4 levels. Then add patterning and/or gradients where you want…

Keith
P
povimage
Aug 30, 2004
As for the gradient… They use a stencil and simply blast more in one area than another within that stencil… Much like in airbrushing… or "burning" in traditional photo printing.

Keith
KD
Kirk_Dickinson
Aug 30, 2004
OK. So they might angle the sandblaster and run around the edge so that one side of the edge gets more blasting.

The creative process is more than building a stencil and blasting it?

I don’t know much about screen printing, but figured that sandblasting was similar. Guess I was wrong.

Kirk
BG
barry_gray
Aug 30, 2004
The one I saw locally was a vinyl cutter plotter that made the masks. In this case the files were vector and that may be the problem you are having. Just a guess.
RS
rrose_selavy
Aug 30, 2004
Maybe it depends on who’s cutting the vinyl (or sandblast paper) but I send simple, high contrast JPG’s to sign shop people to cut vinyl sign elements and sandblast paper all the time.
RS
rrose_selavy
Aug 30, 2004
Maybe it depends on who’s cutting the vinyl (or sandblast paper) but I send simple, high contrast JPG’s to sign shop people to cut vinyl sign elements and sandblast paper all the time.
KD
Kirk_Dickinson
Aug 31, 2004
I am sure that a vinyl cutter has to use a vector file because it is physically cutting sections along a path. Making a sandblast stencil on a vinyl cutter should be the same, I would think.

However, my friend is not using a cutter, She is printing onto a transparancy and using a photographic process to create her stencils. I realize that a vector file would be much better and cleaner, but she is starting with photos and trying to achieve good results. She asked me to help her and I told her I would.

Just trying to figure out the easiest way. I have scanned things and brought them into Illustrator or Corel Draw and then used them as a pattern to create a vector file. Lots of work. Trying to avoid all that work.

Thanks,

Kirk
RS
rrose_selavy
Aug 31, 2004
…and then used them as a pattern to create a vector file. Lots of
work. Trying to avoid all that work.

Talk to whomever is actually going to produce the work and ask them what they need. I assure you that I do this all time time creating cut vinyl graphics and sandblast stencils for motion picture signage and I never send anything to the sign shop but a nice crisp JPG. What they do to it I don’t know nor care. I just know that the work produced is excellent and looks exactly like the image supplied.

For vinyl cutting. Other work often requires other formats including PhotoShop PSD and Illustrator created EPS.
JC
Jan_C._Doddy
Aug 31, 2004
Kirk,
As rrose selavy has mentioned, the best is to find out from the sand blaster what they need.

Go to my site <http://www.doddyphotography.com> then go to the "Newsletter" section, and look for "New Product", this will take you to 2 laser etched 1/2" thick granite images.

I’ve sent this particular printer large color JPG’s and did the rest.

Jan
KD
Kirk_Dickinson
Aug 31, 2004
Thanks for all the replys.

I am not sending anything out to be sandblasted.

My friend is the one with the sandblaster. She knows how to create the stencils once she gets the output on a transparancy from her printer.

What I am trying to figure out is how to prepare the photo in Photoshop for the best results.

Thanks,

Kirk
RS
rrose_selavy
Aug 31, 2004
I am not sending anything out to be sandblasted.

Yes. Sorry. Realized that just after I replied.

Sound like your friend may be hand cutting the ‘stencils’ – yes? If so that’s where the quality of the outline is going to be ultimately controlled. If your outlines are a wee bit ragged they will be smoothed in the final process, perhaps.
KD
Kirk_Dickinson
Aug 31, 2004
rrose selavy,

I don’t understand the process completely. I just got the 2 minute explanation after church. But from how she described it, she prints black on clear plastic from her computer. Then she lays the plastic with the black over some type of special paper(?) and exposes it to light which burns the paper. Then there is some type of chemical wash that washes off the exposed areas.

She then has a stencil with holes in it where the plastic was clear and solid paper where the black was printed.

Sounds very similar to how they do silk screens.

I guess I will need to go over to her shop and see the process, and the problems she is having, before I can either figure out how to help her, or the correct questions to ask.

Thanks,

Kirk

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