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An LCM3 Adventure

Making Photo Etched parts

This is truly where my insanity comes in. I decided, for the first time in my life, to try photo etching at home.

There are very few decent tutorials to do so on modeling sites, but there are tons for circuit board photo etching. So I read a few of those and off I went.

A word of warning. What follows is dangerous. Not ridiculously so, but enough that you MUST wear latex or nitrile gloves, safety glasses, and work in a VERY well ventilated area. When you first mix your chemicals and add the brass you will generate chlorine gas, which can badly damage your lungs. Yes, this is the same chlorine gas used in WW1. Only a small amount will be generated, but even so, be VERY careful and work in a VERY well ventilated environment. Outside and upwind is best.

This is what I found:

- Many sites, especially modeling ones, suggest using ferric chloride as an etchant. This is the traditional stuff to use and can be hard to find. It can also be very expensive and hard to dispose of. Recently the circuit board hobbyists have been moving to a combination of hydrogen peroxide and Muriatic acid, both of which are much more easily available (the hydrogen peroxide is available at the pharmacy and the muriatic acid at almost any renovation store that sells pool supplies, eg Rona, Lowes or Home Depot)

Read the linked page below for additional details and mixing steps.

Mixing Steps Live links

- You can etch almost any brass but the thicker it is, the longer it will take. Most websites say it will take a few minutes to half an hour, but this is for really thin circuit board copper. I made my shields from 0.010 brass, and it took almost 3 hours to etch fully.

- The speed of the reaction is dependent on temperature and mixing, so I put my mixture on top of a food dehydrator turned to low heat, and put an aquarium air bubbler in it. This heats and mixes the chemicals gently. Remember not to put anything metal in the chemicals of they will be eaten by the high strength acid. This heating and mixing is not crucial, but speeds things up and is worth it if you plan to do this more than once. Also make sure it’s a low pressure aquarium pump! You want your mixture to be mixed, not for acid to spray all over the place. Cover your mixture too!

Here’s an image of my setup. Because it was too cold to do it outside when I decided to do this, I put my setup in my airbrush hood, which is vented directly outside, and removed the filter for maximum airflow.

I then took some 0.010 sheet brass and spray-painted it using Mr Surfacer 1000, which I use as a primer. Any lacquer paint should work, and I have since used tremclad from home depot, and both work. I don’t know if an acrylic paint will work, as it needs to resist the acid and I don’t know if the acrylic paints are strong enough.

After painting it, I scratched away the paint in the shape of the outline of the shield I wanted to etch with sewing needle. This outline was made by measuring out the side schematic and comparing it to the images, tracing it in pencil, and then scratching over the pencil.

You then simply drop the brass into the acid mixture, stand well far back, and wait!

Over time your mixture will turn greener and greener as the copper is etched. You then pull it out with tongs while wearing gloves, wash it off VERY WELL with water, and voila, done!

Another note here: the acid mixture can be reused many times according to the instructables website, so you might want to save it in a VERY CLEARLY labeled Tupperware container (non-metal!)

What you end up with is this:

Here you can see 4 shields I made. Three have been removed from the brass and the forth just needs to be snapped out. You can wait until it etches through fully but I preferred to stop it a little ahead of time and flex the shield a little. It then just popped out of the brass.

You can also see how much smaller the Eduard shield is in comparison!

I also cut out a semi-circle and a strip of brass for the cocking lever bulge and soldered it all together. Various other parts like the shoulder rests were made of brass rod and bits of sheet styrene.

The end result was this:

Painting the LCM3 using fairly standard techniques

I cleaned all the parts with Windex and water, let them dry, then primed them with 1:3 dilution of Mr Surfacer 1000 to lacquer thinner.

I used the AK-interactive US olive drab color modulation set, which sprayed well straight from the bottle at 18psi. To emphasize the ribbing of the hull, I sprayed over the ribs with a darker shade of olive drab, using a lighter shade in between the ribs.

I then masked off the bottom hull and airbrushed it with Tamiya’s Hull Red diluted 1:1 with their X-20a thinner.

If you’re curious why I chose this color scheme, I posted about it in the link below.

Colour Scheme Live links

At this point I’m just about 95% certain this is the correct color for the LCM3s at Maastricht. Frankly I wish they were Navy grey since this diorama has A LOT of olive drab, but what can you do, right?