DIY/Home Photoetching

[BrassBuilder]

I don't see DIY photoetching discussed much here. I've posted some of my trials and tribulations on this subject in the past and I am sort of surprised that no one else seems to take part in this.

How come?

On this page:

http://www.scalemotorcars.com/forum/large-scale-cars/2090-military-semi-m915a1-scratchbuild-7.html

I discuss my experience using the Press n Peel Blue with fairly good results. My last parts I made I actually used a photo resist transfer to make my masks. I have to admit that this works even better. With the PnP Blue, I only etched from one side. Doing a little research, I found some advice to etch from both sides at once...even on stock as thin as .002 (which I am using). I have to say this works much MUCH better on the brass. I had pretty good luck etching from one side on the aluminum pop cans though. Where the brass took around 15-20 minutes from one side, it is around 3 or 4 minutes now.

I'm mostly following the directions from these two sites although I deviate a bit from either one:

http://www.prototrains.com/etch1/etch1.html
http://www.instructables.com/id/Dry-Film-Photopolymer-for-making-circuit-boards/

The main difference is that I'm using a 500w lamp for the exposure light.

I'd be happy to post my steps/pictures if anyone is interested.

Here is a shot of the last parts that I etched. It is for version II of my radiator.



Mike

[spinellid82]

Heck yes I am interested!

[BrassBuilder]

LOL. I figured someone would be. I'll get some pictures taken on the next batch that I make.
Thanks
Mike

[BrassBuilder]

Alrighty....
I'm going to break this down into at least a couple of different postings because I want to cover this in detail. Tonite will cover the materials that are needed.

The Chemicals:

Citric Acid. I bought this on ebay to save me the hassle of running all over town looking for it.

Ferric Chloride and Distilled Water. The ferric chloride came from ebay because it was a lot cheaper buying a gallon of it than the little bottles at Radio Shack. The distilled water came from the grocery store.

Sodium Hyrdroxide (Caustic Soda/Lye). I got this bottle at Menards. It is drain cleaner. You can get it on ebay too.

Sodium Carbonate (Soda Ash). Bought this on ebay. Saved me the hassle of trying to find it in town.

Stay tuned....

[BrassBuilder]

The Equipment:

Tupperware or equivalent type of containers. The size will depend on the size/shape of your parts that you need etched. You will need three containers at a minimum: one for the soda ash solution, one for the lye solution, and one for the weak mix of ferric chloride. All of this will be covered later. I also use containers to store the dry soda ash powder, the sparex, and the citric acid. The containers stack nice and neat.

Two (2) sheets of 1/4" clear glass. MAKE SURE THESE DO NOT HAVE A UV FILTER!!! Very important! Mine measure 9" x 12", but they only need to be as big as your largest etch. Since my tank will only do around a 4" x 6" etch, I have plenty of room to grow. This also gives me the option of doing a full sheet etch.

Dry Film Photopolymer. I got mine on ebay. The last batch I had to order from China :( There is a place called Puretch that sells it by a 24" x 10' roll for $49 plus shipping in the US, but I like the easier to handle cut sheets. This stuff needs to be used in very low light conditions otherwise it will start to develop. I usually do my developing at night in my office with the door closed and my computer screen on which gives just enough light to see. The dry film is actually three layers consisting of a top and bottom clear layer and then the blue resist layer in between.

A fine line black magic marker to touch up any bad spots. I don't quite have this perfected yet and still need to touch up the mask at times.

3M Scotchbrite pad or equivalent. I use the maroon colored ones. Any home improvement or hardware store should have this.

Delrin or something similar. I use this as a backing board when I clean the brass sheet. It needs to be smooth otherwise any imperfections will emboss in your thin metal sheeting of choice. I use brass and aluminum. This piece is around 1" thick and it was just something I had on hand.

Some sort of an etchant tank. I got this one at WalMart. It is a miniature aquarium. While you are in the aquarium section, pick up a small heater, a dual outlet pump, and a couple of those small round sheet bubblers. The heater is to heat up the etchant and the bubblers and air pump help circulate the ferric choride. I originally only used a single pump, but I found a dual pump really keeps the ferric chloride agitated. I have two strips of the bubblers thingies in the bottom of the tank. Adjust your heater to the size of tank you get. The bigger the tank, the bigger the heater. In my case, I got around a 2 quart tank and used the smallest heater they had. I shouldn't really have to mention this....but....please....please....do not get a metal container! That will be VERY VERY BAD.

Transparency. I had to get this on ebay. I could not find the stuff in town. Evidently no one uses overhead projectors any more.

Light. There are a few options here. I am using a 500w work light from Menards. It is important to remove the front glass from this as it has a UV filter in it. In my experience, it takes about 3 minutes to expose the dry film using the 500w light. I've also read where a 15w fluorescent was used. The exposure took about 15 minutes using that. If it is a sunny day out, the sun could be used for a natural light source. From research, the exposure time is about one minute using the sun. I've had great luck with the work light. It took me a few tries to find my exposure time. Six minutes was way to long and two minutes wasn't quite enough.

Laminator. I got this one at WalMart for around $25. It was the only one they had in stock. I use the 5 mil setting for .002 brass sheet. I suspect I can go possibly .003 or .004 thick brass, but I think the .004 will be pushing it for thickness. Each mil is .001" thick. Mine has 3 mil and 5 mil settings. I tried the 3 mil setting and it tore the dry film as it went through. My wife uses this now to laminate her recipes. :)

Laser Printer. Mine is a Canon Color ImageClass MF8380cdw. You don't need a color laser printer. You just need access to one that prints black. If you can find the transparency material that will print in an inkjet, you could probably use one of those. Unlike the thermal transfer method, the ink on your mask never transfers to your material. I can use my mask numerous times.

I forgot to get a picture of these last two...but you also need a spray bottle for the distilled water and a box of thin rubber gloves. I got my gloves at Advanced Auto. They are a "Derma-Lite" brand. The box also has "Lightly powdered nitrile gloves". This is just to protect your hands from all the chemicals.

Stay tuned Bat fans.....

[BrassBuilder]

Optional:

Slow Cooker. I use this to clean the brass after it gets run through the lye solution. The lye really discolors the brass sheet and running it through the slow cooker with the Sparex #2, it comes out nice and clean.

Sparex #2. I got this at a jewelry store. They had to order it in though. I suspect you can get the stuff on ebay. I don't remember the mixing ratio, but just follow the directions on the package.

Stay tuned for more Bat fans...

[BrassBuilder]

Things to do prior to your first etch:

1. "Edinburgh Etch" mix.
I use the following mix in lieu of using the ferric chloride straight from the bottle.

FORMULA: 4 parts ferric chloride solution + 1 part citric acid solution

EXAMPLE: 4 liters ferric chloride solution + 1 liter hot water mixed with 300ml citric acid powder

See this site for some excellent reading on this subject:

nontoxicprint | Nontoxic Printmaking & Printed Art

As I did not mix a 5 liter batch at once, I had to adjust my amounts proportionally.

There are alternatives including mixing the ferric chloride 1:1 with distilled water to slow down the etch time. There is also a mix using hydrochloric acid and hydrogen peroxide that is supposed to work pretty good, but I've never used it as I can't stand hydrochloric acid. You could also use the ferric chloride straight.

-------------------------------------------------

2. Weak ferric chloride solution.
Take one of the tupperware containers (or equivalent) and mix a weak mixture of distilled water and ferric chloride. I'm guessing I used maybe a couple of cups of distilled water and probably around 2-3 tablespoons of ferric chloride.

This site:
http://www.prototrains.com/etch1/etch1.html
says to use a 1:100 mix.

-------------------------------------------------

3. Soda Ash (Sodium Carbonate) Solution
In another container, mix a 1% soda ash to a liter of water. Again...since I did not use a full liter of distilled water (probably closer to 2-3 cups) I had to ration this out. I think I used around a teaspoon or two of soda ash to the distilled water. I really don't think having this a little strong is going to hurt much.

-------------------------------------------------

4. Lye (Sodium Hyrdroxide) Solution
This is a 2-5% mix with distilled water. According to some of the research I've done on this, it is better to add the water to the lye if you are using the crystals. I slowly added the lye to the water without any issues. I probably used a tablespoon or two to 2-3 cups of water.

There is a lot to get ready, but once everything is lined up, then the fun can finally start!

Stay tuned when I start an etching (maybe tomorrow night).

Mike

[BrassBuilder]

Websites that have great info:

A Home Photoetching Operation, Chapter 1
Puretch Photopolymer Instructions
Dry Film Photopolymer for making circuit boards
nontoxicprint | Nontoxic Printmaking & Printed Art

[BrassBuilder]

The Artwork

Using the dry film method requires a little different procedure for the artwork compared to the Press n Peel Blue or any toner transfer method for that matter. For a toner transfer, you need to make a positive image...i.e....anything that you DO NOT want ate away will be black. In the dry film method, anything that you WANT ate away will be black.

You have a number of options for making the artwork. Any drawing program will work. GIMP is especially good and easy to use for drawing and it has the features to reverse your image colors and reversing your image. I find it is easier to draw the mask out as a positive image and then reverse the colors to get your negative image. For a dual sided etch, you also need a reverse image so things will line up...but that is only because I like keeping the printed side inside on both sheets....but I am getting ahead of myself. In my artwork, I used an Excel spreadsheet and ended up with an image that was symmetrical which means that I did not need to do a reverse image. I adjusted the rows and columns until I had my image set up and then filled in the areas with black that I wanted etched. Since I am now etching from both sides, I needed a way to keep the image together...hence...the tabs between each part. When I etched from one side, I used contact paper to protect the back side from the etching and that kept everything together.

Here is the artwork printed out on the transparency.

You want to cut it apart and tape it together in the middle....so when....

...you fold it over, the two images line up perfectly. And then when....

...you insert your material between the two sheets, you can be sure they line up perfectly. But we have a few things to do before we get to this part.

Stay tuned for the next exciting chapter Bat fans. Same Bat channel. Same Bat time.

Mike

[karmodeler2]

Hey Mike,
I hate to ask, but can't see in your thread where you transfer the image onto the brass. Are you drawing your artwork, sending it to your printer which is loaded with transparent film. Then taking the "copy" and laying it in the brass and then sending it through the laminator to transfer the image to the brass? Are you also using the Photo Resist Transfer on the brass first and that's why you don't loose your image?
Thanks. I really want to get into this and need as much help as possible and I appreciate you taking the time to post this tutorial. It is very helpful.
David

[BrassBuilder]

Hi David,
You're jumping ahead of me :)

I need to get to that part yet.

You don't quite have the order right with the laminator. I plan on running a few pieces through tonite and then I can get this updated for you. The pictures will help explain this immensely.

Mike

[BrassBuilder]

Alrighty Bat fans....ready for the next exciting chapter???

Cleaning the Material

The first step is to get the material cleaned. From here on out, you want to wear your rubber gloves so that no skin contaminants gets on the metal and no chemicals get on you. You will also need your weak mix of ferric chloride, a small pad of the maroon scotchbrite, your flat surface to scuff up the metal (in my case, a chunk of delrin), and a spray bottle of distilled water. For the initial cleaning, you can just use TAP water. I soak the scratch pad in water and then work the metal across the long way, then across the narrow way, and then back across the long way. If I remember, I usually even use a circular motion in between there. Do both sides. Rinse out your scratch pad and the work surface on a regular basis. Make sure the material is nice and shiny and there are no creases. If the scratch pad catches a corner and creases the material, I would start over.

Once you are happy that the material is clean, spray it down with distilled water and rinse all the tap water off.

Drop the material in the weak solution of ferric chloride. You do not have to dry the metal before dropping it in. The solution already has distilled water in it. Let it soak for 15 seconds or so. This will put a light etch on it.

After taking it out of the etch bath, rinse it with distilled water again.

Quickly dry the metal with a paper towel. You do not want to leave splotches on the metal. You should have a fairly even sheen across the metal when done.

While I am here, you notice the laundry tub has that super yellowish brown stain? This is where I rinse my parts off after etching. It takes very little to stain a large surface. You will see more staining on my work bench where I do the etching too. This stuff is nasty for staining.

My wife was not a happy camper that I did that to the laundry tub....

Next up....applying the resist.

Mike

[BrassBuilder]

Applying the Resist

From here on out, you need to be in a low light room. I've been doing this at night so that I don't have to completely block my windows off. I leave the computer monitor on for a little light so that I can see what I am doing.

The first step is to cut the resist down to size. Keep it about 1/2" larger or so all the way around your sheet metal. Using tape, you should be able to grab one of the top layers of the clear and pull it off.

Once you have the layer off, place the sheet metal and the resist on a sheet of paper....REMEMBER WHICH SIDE YOU TOOK THE CLEAR OFF OF! HAVE THAT SIDE ON THE METAL and tape it at the bottom where it will run through the laminator.

This part is where things can go bad in a hurry. Heat up your laminator per the manufacturer instructions. Run the sheet of paper with your metal and the resist with the tape end first. HOPEFULLY...you won't get any creases or tears. I've only had a couple of sheets that bonded perfectly. I seem to get an air bubble or a crease here and there. You can salvage it if you only have some creases or air bubbles. You will just have to clean up the mask with a marker as needed on bare spots. If it tears, pull the top layer of clear off and toss the metal in the lye solution, strip the resist and start over. OR...toss the whole thing in the garbage and start over.

In lieu of a laminator, you can also use an iron. I'm going to try that one of these days. In fact, I will have to try it. I have some .010" brass to etch and it will be too thick for the laminator.

Cut out around your metal, pull the paper off of the metal on the back side and repeat all of these steps for the other side.

Next up...Exposure.

[BrassBuilder]

Exposure

You should now have a sheet of metal that is laminated on both sides with resist. You should have also left the top layer of the clear on it yet on both sides. If you got in a hurry and pulled the top layer off....either start over or continue on and see what happens.

Take your double sided artwork and your transparency that you made earlier and place your laminated metal in between the two layers. Place that whole thing between your two layers of glass.

My high tech exposure unit. Yeah...I hold that light for 3 minutes while it exposes. The light is approximately 15" from the artwork. I am going to build a stand for the light one of these days.

Once you've exposed it under the light for 3 minutes, CAREFULLY flip the artwork/metal over and expose the other side for three minutes. You do not want the sheet metal to slide out of place. If your metal is sticking out of the end of the transparency a little, you could tape it in place. That way, you will be sure it doesn't move. Having it move is very very bad.

Once you have both sides exposed, you should be able to see a faint "burned in" mask of your artwork on the resist. If you don't, you either forgot to put resist on that side (yeah...been there....done that) or you did not let it develop long enough. If you can see the image, go ahead and peel off the top layer of the clear. I use a piece of scotch tape to grab a corner and it usually pulls right up. If it doesn't...try another corner....if it still doesn't...well....I'd hate to say this, but you probably put the wrong side out when you laminated it. Repeat for the other side.

Stay tuned for the Developing.

[BrassBuilder]

Developing

You can turn the lights on now :)

Take your metal and place it in the tub of the soda ash solution. Let it sit for a minute or two and this will develop the resist and loosen the resist from the bare areas.

Once done, you should have a sheet of metal with your exposed artwork clearly visible. As you can see, I have a few spots to touch up. This is actually one of my worse ones for touch ups.

Here is the completed mask with the areas needing a little touch up.

I won't be doing the etching tonite as I want to get a few more sheets made so that I can run a bunch through at once.

Stay tuned Bat fans. Same Bat channel.

Mike