Introduction

I decided to start this blog to show the process I am going through to replicate some hard to find lenses for vintage emergency vehicles.  After being around the professional car (ambulances, hearses, limos) community for a while, and owning an ambulance myself for a while, I noticed that some of them had special lights on them, sometimes repurposed from something else, and occasionally purpose-built for a specific vehicle.  Due to the age of these vehicles and the type of light used, parts became increasingly scarce as the vehicles became more and more obsolete. One example of this is the Ful-Vu light, made specifically for Miller-Meteor ambulances over a period of 5 years or so, from the late 60's to the early 70's:

Ful-Vu light with polished base.

 

Typical Ful-Vu 4 corner installation on Miller-Meteor Cadillac Ambulance.

 

 

Another example of a hard to find lens is the S & M Lamp Co. Oval Light:

 

 

 

This light started out being used in the 30's as fog and driving lamps in yellow or clear.  It may have been used back then in red on emergency vehicles or as a stop lamp, but I don't recall seeing any that far back.  It is actually a metal bucket with a bulb in it, with a clear or colored glass lens over top of it.  For whatever reason, they showed up on certain emergency vehicles primarily in the late 50's and early 60's.  There is also some debate as to whether or not they were used on Superior school busses in the 60's.  Some say they were, others say the busses only used an oval plastic lens, which looks similar, but is a completely different size and mounts differently.  Whatever the case, the busses didn't use oval shaped lights for very long, so you can pretty much forget about finding replacement lenses in junkyards today.

 

(By the way, if you think the lens is rare, try finding a replacement TRIM RING today!  Oh boy!  A competent metal-brasher can hammer out a decent replica bucket, given enough of a good one to go off of, and we are discussing how to replace the lens here, but fabricating the fragile trim ring that holds the two together, and getting it into the proper oval shape, then getting it CHROMED takes a true artist!  I would suggest you snatch up any you find for less than $100, as someone somewhere will have been looking for a very long time!)

 

 

The reason these lenses are rare is because they were made of glass.  Glass is expensive to produce in limited quantities, and as the fixtures became more and more obsolete, production of replacement parts stopped.  What you are left with is whatever parts were produced during the run.  Of course, glass also breaks if not handled or cared for properly, so a certain amount of the remaining stock dies of attrition.  As these old vehicles are resurrected, it is this kind of part that keeps you from finishing your restoration.  Now, there probably will never be a big enough market to get anyone to invest in reproducing these lenses in glass as they were originally, but it is not too far-fetched to make a reasonable facsimile, IF you can come up with an original to start the process.  Otherwise you would be forced to have someone re-prototype the original, at considerable cost.

 

I am lucky enough to have secured a couple of originals to start the process:

 

 

Ful-Vu lens (left) and S&M Oval Light (right)

 

 

Of course, I did some tests with other, non-critical glass lenses (more $$$) to make sure the process wouldn't damage the precious originals.

 

 

 

Raw Materials

Way back, probably 10 years ago, I was at some auto-related something-or-other and came across a booth that was displaying Alumilite products, a system for making molds of parts and casting new ones out of various resins.  One of the things they were showing was a reproduction of a steering wheel that they had made from an original:  

Alumilite Steering Wheel Mold.

  I thought that was pretty cool.  Little did I know at the time that to do what they did, you could probably go out and buy the same rare steering wheel for what it would cost in materials, but I thought the process was intriguing, so I took a brochure.  They also showed the process of making a replica tail light:

Making a tail light.

 

I didn't have any need for it at the time, but like everything else, I never throw anything away, so when I DID have a need for it I had the company name handy (after digging for it for a couple hours).

 

The process ends up being more expensive than you might think, mainly because a little bit does NOT go a long way, but if you need parts that just are not available any more it may be your only alternative.  You really have to consider the demand for a particular item, because that's the way to recoup your investment, by making enough for other people to sell and make some of your money back.  This is not a system where you can just say "I can't find another tail light at a reasonable price, so I'll just reproduce my good one for $30."  As I go into further detail, you will see the work that is involved and how much product is needed.  The initial investment can escalate quickly, depending on how big of a part you are trying to reproduce, and how well you want it to turn out.

These are two of the products I will be using to make molds:

Alumilite Quick Set and High Strength 3

   

 

Enough for HALF a mold!

 

 

In general, 1 pound of mold making silicone is enough to make 21 square inches of mold.  Let that sink in a bit.  A 1 cubic foot mold is 1728 cubic inches (12"x12"x12")!  For the Ful-Vu lens, the mold ended up being roughly 6"x6"x12", or 1/4 cubic foot, or 432 cubic inches!  Divide that by 21 and you will see you need roughly 20 boxes of product to make the mold, at a retail of $30 a piece!  Now, the object you are casting takes up some space, and there are some other tricks you can use so you don't need as much casting material, plus if you buy in bulk or look for discounts you can save some money, but you can see how something that starts out as a whim suddenly becomes a major investment!  All told, just to do the Ful-Vu lens (which is pretty big) I estimate I have already spent close to $400 on this project, and that doesn't include the cost to acquire the original part to cast from ($250)!  You're going to want to make sure you really want to do this before you get started!

 

 

You will also want to get a number of cheap utensils for the various measuring and mixing of silicones and resins you will have to do. I have not had much luck cleaning anything after use, so you really want to find disposable stuff at places like dollar stores.  You can also get glass measuring cups at places like Goodwill that you can get a few uses out of before you have to get rid of them.

 

 

Dollar Tree mixing stuff

 

 

For mixing cups, you want something as smooth as possible on the inside, to make it easier to get your mixed liquid out of the cup.  A lot of what you will use is measured precisely by weight or volume (make sure you know which!), so you can really mess things up by not getting everything out of the mixing cups.  Things like Solo cups have ridges on the inside, which make it difficult to get everything out of them.  A pouring spout or corner also makes things easier, but is not necessary.

   

 

 

Preparation

Before getting started on a mold for the Ful-Vu lens, there were a few things I wanted to take care of.  As luck would have it, I had a broken lens that I could experiment with to try some things. For any given casting project, there are probably a number of different ways of going about it.  Having already completed most of what is detailed here before writing about it, there are probably a few things I would change, but since it worked I will write about what I did, then add what I should have done. Because of the shape of the Ful-Vu lens, I knew it would have to be some sort of two-part mold, rather than just a simple one piece.  I struggled for a while with the design, but eventually came up with an idea I thought would work.  The first thing I needed to figure out was how to non-permanently attach the lens to the mold box I was constructing, as I didn't want it to move around as I was pouring the first half of the mold.  This is where the broken lens was helpful.  I could try some different adhesives without worrying about damaging my good lens.

 

I decided to try using Mighty Mend-It to fasten the lens to the wood I was using for my mold box, as it shouldn't be permanent on these materials, yet should bond good enough to keep the lens from moving.

   

Thin bead of adhesive around lens should keep silicone from going underneath.

 

I let this set up overnight and then made sure it would hold tight, and that I could remove it again without damage.

 

 

After I was satisfied with my adhesive solution, I started working on the box that would contain the mold as it was setting up and hardening:

 

 

 

 

The basic box size is not much bigger than the outside dimensions of the lens.  For most objects, you shouldn't need more than a half inch of thickness at any given point.  Even less thickness would probably work, but I didn't want to take any chances.

 

Because this was going to be a two part mold, and I would eventually pour the resin for the lens from the top (the bottom in the picture above), I needed the box to be the exact height as the lens itself.  The reason will become clear later.  This is one of the things I would do differently if I were making another mold, but it ended up working ok as-is.

 

So first I got an exact measurement of the height of the lens:

 

This picture is not dead on, but you can see the height is just about 3 3/16" high.

 

 

So I cut the sides of the box down to 3 3/16" on my table saw, and screwed everything together:

 

Here it is with the lens set in place.

 

At this point we are just about ready to pour, however I do want to mention one other thing.  While this lens is in great shape overall, you probably noticed it has a few defects:

 

Decent sized chip out of the bottom.

 

Some more minor chipping along the bottom edge.

 

 

As this story goes on, I will discuss a couple different ways these defects might be dealt with during the process, depending on how much time or money you want to devote to them.

 

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.

 

 

Clean-up and preparing to pour second half of mold

So, when we left off, this was where we were:

 

Once the mold has had time to dry (anywhere from 24-48 hours, depending on size and materials), you can start cleaning it up and preparing for the next step.

 

Cutting away excess mold materials.

 

Here you can see the holes that were left from the metal posts I suspended in the mold.

 

The height of the silicone is perfectly level with the lens and the side of the box.

 

Remember the chip in the glass?  The silicone has filled it in.  We will leave it for now so the other side of the mold will pour properly, then cut it out so future lenses will not have a chip in them.

The second part of the mold will have a 1 inch base, so we will need to extend the box by that much to create it:

 

I didn't plan it this way, but the pieces of wood I added give a nice place to attach the extension.  This could have been done on the outside too, but having them on the inside also means we will use a little less silicone on the second part of the mold.

 

 

 This time I made an effort to "fill up" as much space as I could for the second mold with other, less expensive materials than silicone.  Like the wood pieces I added before, I did this wherever I thought it wouldn't affect the integrity of the mold:

This is about ready to pour.  The wood in the center does not go all the way to the bottom, and the "X" portion is suspended above the first part of the mold so that there will be a clean mating of the two mold halves all the way around.  All of this wood will remain in the second part of the mold.  I chose to make the metal posts a part of the second half of the mold for durability.  If I didn't, the posts would have been molded out of silicone, and probably wouldn't last long.

 

Pouring the second half of the mold

So now I have made all the inserts for the second half of the mold and I am ready to pour the silicone around it.

 

This time I am using a different silicone, mainly because it is what is locally available after I bought out all the Quick Set from Hobby Lobby.  The High Strength is much more flexible than the Quick Set, if your project requires it, but may be less durable over time.  In hindsight, I probably should have waited and used all Quick Set, but Hobby Lobby only stocks one container of each at any given time, and doesn't restock them right away, so I end up driving all over town to get enough.

 

 

The High Strength is more pink in color.  I removed the insert for now to get a better pour into the middle of the lens.

 

 

After pouring a decent amount into the lens, I re-assembled the rest of the box and the insert and finished the pour.

 

 

As you can see, I taped up the seam between my box halves.  As thick as this stuff is to pour, it seems to find its way through the smallest of cracks and make a mess.  Now this will set up for another day or two, and then we can undo everything and see what we got.