Pouring the first half of the mold

So, we have our box constructed, our lens set in place so it doesn't move, now we are at the point of no return, where we can start wasting copious amounts of money and resources on a project only a few people will probably care about.  Awesome!   The first step, which will get repeated many times (seven, to be exact), is to get the silicone mold making material open and mixed.  It looks like this:

Silicone (left) and catalyst.

 

You simply mix the two together until they are a uniform color.  Both types of silicones I used have a fairly long "open" time (the time you have to work with them until they start to set up and harden), about 20 minutes or so, so there is ample time to mix them well and get everything out of the containers, and still be able to pour.  The quantities they give you of silicone and catalyst are a 1:1 mix ratio, meaning you use all of each of them if you want to mix the entire amount.  If you only needed half, you would use half the silicone and half the catalyst.

 

First mini-crisis:

 

You have to shake the catalyst first, it says so right in the instructions you ignored!

 

It's supposed to look like this when you first pour the catalyst in!

 

As per the instructions (the what?), the catalyst can settle during storage, so it should be shaken before being poured into the silicone.  Likewise, the silicone can settle during storage too, so it is best to stir it a little bit before mixing in the catalyst.  This is much more crucial if you are only using a portion of the silicone, and not the full amount, as it all gets mixed well after you pour one into the other, but it's probably best to follow the rules no matter what.

 

When ready to pour, silicone/catalyst mix should be a uniform color, as seen here.

 

Just keep pouring and mixing until you reach the top...

 

 

...or in this case, don't reach the top.  Turns out I didn't have quite enough silicone mix to fill my mold. This is not a huge problem, as you can add more silicone later (silicone will stick to silicone), but I chose a different route.  First of all, it helps on a two part mold to add something to register the two parts to each other.  Sometimes it can be as simple as adding something to your mold that will make a dimple or hole in it, and the corresponding dimple or "peg" will be created when you pour the second half of the mold.  This is what I set out to do, but as you will see later, rather than making the second part of this out of silicone I just used the part itself and made it a part of the mold.

 

I made these pieces of wood with metal dowels attached to them initially to create holes in my mold that would become registration points for the second half of the mold (this will become more clear later).

 

After inserting them the silicone still wasn't up to the level of the side of the box, so I inserted some lengths of wood into the corners of the box before the silicone set up which raised the silicone level just enough so it would be where it needed to be:

I tried not to have the silicone run over the edges, but once it hardens its not too hard to clean up.

 

 

Speaking of cleaning up:

 

   

Did I mention it helps to have a sink/work area you don't care much about?

 

Once we get this mess cleaned up we will continue with part 2.