# Fake chain made from Foam Backer Rod



## cadcoke5 (Feb 23, 2013)

I posted this idea on a thread about PVC chain, and just tested the idea of making chain from what is called "backer rod" or "caulk saver". It is used in the construction industry to put between slabs of concrete, and caulk is applied over top. 

The basic idea is to wrap the stuff around a form, and then heat it until is starts to soften. Then cut the loops off, and glue the loops together into a chain. Here are the details;

The backing rod I found was "Frost King" brand at Lowes for $4. It was 5/8" dia x 20ft long. Here is a direct link, 
http://www.lowes.com/pd_127194-1410-C23H___?productId=3010567&pl=1&Ntt=backer+rod

They also have 3/4" x 20' for $6 . This is grey colored, and is marked #4 recycling, which means it is low-density polyethylene. This is what we want, because it can be reformed with heat. Some backing rods are make from polyurethane, which we DON'T want.

Backing rod is available in a variety of sizes. I have seen it online is sizes up to 1" diameter x 100ft roll for $21 including shipping. For my test I used 5/8". 

1) Wrap foam around mandrel, and fasten into place. 
My test mandrel was a can of green beans, that I had flattened to be more typical chain shape. And while chain, especially historically, is in a variety of shape, I was concerned about the foam holing its shape and not distorting unrealistically. So, a pure round shape may not be the best choice for that reason. An alternative mandrel could be made by a 2x4, with its corners rounded out. Make what will fit your oven. I used a simple paper clip, bent into a shape to grip the can and the foam. 








2) Heat in oven at 200 deg F for 10 minutes. Foam is, by its nature, insulating. So, it takes time for the warmth to get inside. More time will be necessary if you use foam thicker than 5/8". I actually tried my convection oven, but it only goes down to 250 deg. I melted some chain on my first test, because the hot air blows out much hotter than that. So, I simply pre-heated it to 250 deg for several minutes to permit the entire convection oven to get that hot, and turned it off before I put the foam coil inside.

3) Cool for 10 minutes.

4) Cut loops off of the mandrel. I used scissors, but a razor is probably a better choice.








5) Glue the loops together. I used a low-temperature hot-melt glue gun. My gun only goes down to 250 Deg, which is well above the 203 deg that the polyetlylene can stand. But, I was successful by carefully squeezing out a bulb of glue about the size of a larger ball-headed straight pin. Then, spread that drop out with the side of the glue gun, by wiping up-down and side-to-side. Then immediately press the two edges together. Another person noted that it is best to glue half of the links together, and then join the remaining ones to them.








Other notes;

The shape ended up be a little elliptical. I think the diameter of the backer rod was just a bit too thin for that shape.. 3/4" would probably be better. If I would have flattened the loops a bit more, so that it was 5" x 2 1/2", then the 5/8" rod would have looked right. But, I don't know how to get that shape. As it is, the links tend to stretch out when I put any load on it. Though for an indoor static display, it is fine.

In my case, this is to be used in a theatrical production of Dickens' Christmas Carol for the Jacob Marley character. So, some of the chain must be used to hold lock boxes and other items. They will also be made of foam, but I am a little concerned that my foam chain will not stand up to the forces. So, I think we will use plastic chain for the items we will be dragging. And while the medium-grey appearance is ideal for the character, we will also want to add some black light. So, adding some fluorescent paint would help a bit. Painting this type of plastic is certainly not an easy task. I have read that some have used 3M Super 77 spray adhesive as a primer. I wonder if simply mixing some contact cement with pigment might work, and permit you to use a little more artistry to control the appearance.

For those who might use this outside, the light weight will permit it to blow in the wind, in a very un-chain like manner.

For my 5/8" backer rod, I was able to get 6 loops around the can that was 4 1/2" long. It used 6' (72") of rod, and resulted in links that were 4 1/2" by 3 1/2". 6 links formed a chain that was 22" long. So, it was approximately 1/3 of the size of unrolled length. 

The final cost of the chain I made was $0.64 per foot. For price comparison, the bulk chain of comparable size at MrChain.com is $1.33/ft and some halloween chain on E-bay is $2.33/ft. The halloween specific stuff is nicely colored and often comes with things like shackles and locks, which are a good addition. We may purchase some of those just to get the accessories for Jacob Marley.

-Joe


----------



## bringjoy (Aug 28, 2005)

This is an awesome idea and it looks great! Thanks so much for posting


----------



## cadcoke5 (Feb 23, 2013)

Here is an update on the costume. I just finished the run of "Scrooge!"- a musical version of Dickens' Christmas Carol. It was performed at Cavod Academy of the Arts in New Holland PA the past two weekends with most performances being sold-out.

Note that while I made the chain itself, other people did the costume and makeup. The picture is a little outdated because we re-arranged things a bit, and added some light gauge real chain to one arm. This was long enough to touch the ground, and added some nice realistic chain sounds, which the microphone picked up surprisingly well.

Inside the lock-boxes I added some metal desert cups, which would rattle, though it was not an ideal sound. I was trying to make them sound like there were loose coins inside, but at least they sounded like they were made of metal, rather than cardboard and foam.

Also, the chain that was made with pipe insulation was not nearly as strong as the backing-rod foam chain. I eventually threaded a black cord through the center of the chain, to carry the weigh. It may not have been necessary for chains made with the backing rod, but I didn't want to risk them coming apart like they did in one performance.

The close up picture is after 9 performances, and shows the wear. My chains dragged behind me, and my exit had me draggin them over the edge of a platform. So, they got a lot of wear. The paint they used on the black pipe insulation was not that durable, and the texture difference between the smooth outside vs, the cut surfaces certainly showed with time. The gray backing rod was pretty much the color they wanted, and they just hit it with a little paint to introduce some variation. Polyethylene is a difficult thing to get anything to stick to. Use a spray paint specifically designed for plastics, if you want any sort of wear resistance.

-Joe


----------



## Saruman of Many Colours (Sep 8, 2010)

Very nicely done! Looks quite good.


----------



## Rigormortor (Sep 7, 2009)

Very cool, im going to get some of the foam at Lowes maybe this weekend and add that to the props in building.
I need chains....


----------

