Monday, 21 January 2013

It's not hand painted, but it is hand done.

This is a quick job for a client that wanted something different for their washroom signs. I did a heritage building a few years back, and had  produces molds for the washroom and mechanical room doors. The masters for the molds were created by first cutting the letters and border from 1/4 MDF board, and then epoxied them to another piece of MDF, and then shaped the backing piece to match the boarder profile. This is not a job for the faint of heart, as the fingers tend to get a little close to the scroll saw blade. Once I had it glued together, I used a Dermal tool to create the background texture. You may think it would take a lot of time to do, but it only took around 15 minutes per sign. Once I had the texture, and final sanding finished, I brushed a few coats of epoxy on to seal the letters and boarder to the backing plate, this creates a molded look to the sign. You must take care with this step, as you don't want to fill the background detail with epoxy. Once I was satisfied with the piece, it was time to make a mold. I used a 2 part urethane rubber mold compound for this step. Two things you want to watch for,  build a good bridge around the piece to keep the rubber in place, and make sure you get no air trapped when pouring the molding compound. A good trick is to use a brush to apply the rubber to the surface, and then pour the compound. This helps to eliminate the chance of air getting trapped, thus ruining the mold. Once you have the mold, the rest is pretty simple. I use a urethane casting resin for the actual sign. Depending on the final color, I will tint the resin to match the final color of the sign. For this job they wanted a gold finish, so I tinted the resin with Bronze powder. That way it takes very little paint to get the desired effect. Once the clean-up was done, I applied a few coats of bronze powder carried in clear, using an air brush. Here's a few progress pictures. Hope you enjoyed the post.

This is the masters that was used to make the mold. The ladies sign in the gold color was a test cast. Unfortunately I didn't take any pictures when creating the master or mold, as this was before I started blogging.

Here is the finished rubber mold, ready to use for the casting. When using Urethane for casting, you want to make sure to use a release agent so as not to wreck the mold. You may not have a problem, but why take a chance.

 I mix the bronze powder into the "A" component and mix thoroughly. Then add the "B" component to activate the mix. You have a couple of minutes to pour it in the mold before it starts to go off. Not a good time to answer the phone.

Now it's just a matter of pouring the resin in the mold. I find that if you start by pouring it in the lowest parts of the mold, then let it flow to the rest of the mold, it will chasing the air out as you go. This way you don't trap air in a letter or part of the border. 

  The finished cast before the clean-up. I lay the signs on the face so they will cure flat, as the backs of the casts can be a little uneven. I will then let then sit over-nite so the resin can cure.

 And here's the finished sign, complete with paint. I could go in and apply a glaze to darken the background, but it's not needed for this job. If you have any questions, feel free to leave a comment, or send me an email.
Thanks for taking the time to drop by.

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