Introduction: Preserving (pieces Of) Pittsburgh's Roberto Clemente Bridge
Every year during PicklesBURGH the City closes the Roberto Clement Bridge off to vehicular traffic and opens it up to pedestrians and business selling all things pickle related.
And every year I take the opportunity to check out the parts of the deck that are usually open only to vehicles and harvest pieces of the bridge that have fallen off. Sort of like collecting leaves.
Don't worry, I didn't use a pickaxe on the bridge. But if I see a piece, particularly one with some iconic yellow paint still attached, I collect it. In 2020 the bridge is undergoing a much-needed overhaul so it may be the last time I am able to collect these bridge pieces.
I decided to preserve the pieces I do have.
Lately, I've been having fun playing around with casting resins. So I got out some molds and encased bits of the bridge circa 2019 in clear casting resin. They came out pretty cool! Here's how you can go about preserving something special to you.
Here's what you'll need if you want to follow this Instructable exactly.
- Roberto Clemente Bridge - preferably closed off to cars/trucks/motorcycles. This is where you get metal bridge pieces. DON'T CHIP PIECES OFF THE BRIDGE.
- Casting Resin - I used Art 'N Glow resin. Two parts, resin and hardener. It works well if you measure it properly.
- Food Scale - any inexpensive food scale will work. There are a bunch available on Amazon if you don't already have one. It's so you can more easily measure out the proper amount of resin and hardener.
- Vacuum chamber - This is so you can get bubbles out of the mixed resin. Fewer bubbles = more clear. You really need this if you want to see what you're putting in the resin. A kit with a decent pot with a pump will cost anywhere between $100 to $150 USD. Amazon or eBay are good places to get one.
- Molds - I used a combination of molds and will get into what I used and why later in the Instructable.
- Mold Release - so your casted resin isn't too stuck to the mold. I use Mann Ease Release 200 but there are plenty on the market.
Polishing supplies and a pressure pot.
There are all sorts of ways and methods to polish resin. Here's a very thorough Instructable on How to Polish Resin.
A pressure pot is the opposite of a vacuum chamber, instead of pumping out the bubbles it squeezes them down until they are super small. Many people swear by pressure pots but they are fiddly to set up initially so do your research.
Step 1: Harvest Your Bridge Pieces.
I love PicklesBURGH. It's probably my favorite summer festival in Pittsburgh. (Jeff Goldblum Day is a close second though!) One of the really cool things about PicklesBURGH - besides all the tasty pickle treats - is that you get to hang out on the part of the Roberto Clemente Bridge that is usually open only to automotive traffic.
This is important because the City of Pittsburgh does a pretty good job cleaning and maintaining the sidewalks on either side of the bridge. There are hardly ever any metal bits that you can harvest from those areas. However, the road portion of the bridge doesn't get as much of a sweep. So when it's open it for foot traffic there's usually some choice bits of metal that have rusted and fallen off the bridge. Let's face it, winters are rough on any road surface, but metal gets hit particularly hard.
I just keep my eyes peeled and have a ziplock bag handy. I'm also not too greedy when it comes to snagging those metal bits.
Step 2: Get Your Molds Ready!
I used a combination of found molds. I used some McDonald's syrup containers and some old mini-muffin pans for my molds. You can get creative here re-using things like soda cans, yogurt containers, etc.
If you want a super easy solution, get some silicone mini muffin pans cheap on amazon. They work really well for casting. I've linked a silicone mold with a glossy finish. If you use that or something similar, you may get some really good results on the bottom and sides of your cast pieces (see final step). There are also purpose-made resin casting molds you can get from craft websites and of course from Amazon.
Don't forget to spray your molds with the mold release spray.
Step 3: Mix Resin & Get Rid of Those Pesky Bubbles!
Put your food scale in grams. Put a wax-free cup on the scale and pour some resin in the cup. Next, pour an equal amount of hardener in the cup. Pour in a deliberate fashion. You should probably be wearing gloves - nitrile or latex.
I mix with a wood tongue depressor. You can get a box of 100 for $5.00. That should last you a while.
Don't whisk it like you're beating an egg. You will put a lot of air in the resin that way. After you've thoroughly mixed your resin and hardener you have to get rid of all the air that you did introduce.
Put the cup of mixed resin in the vacuum chamber, seal it off, and turn the air pump on. It'll start sucking the air out and bubbles - like soap suds - will start to form. Before it overflows the cup, release the vacuum pressure so it shrinks. Then put the vacuum back on. Rinse and repeat for as many times as you think you need. You'll get the hang of it.
Step 4: Pour the Resin in the Molds + Wait, Then Go Back and Repeat the Previous Step.
You only need enough resin for HALF of your mold. So if you are going to encase a few pieces of metal, you'll need resin for half all the pours you will be making. Why only half?
Because metal won't magically float in the middle!
The easiest thing to do is pour the resin, cover it with something so dust or hair doesn't contaminate it, and wait overnight. After 24 hours the resin will have cured hard enough so that you can place your bridge piece on it and then pour resin over it. You won't be able to see the line.
Step 5: Remove and Take Some Photos!
After a day the resin of pretty hard - not 100% but hard enough to handle. If you removed all the air you should have some really clear castings. Here are a few of mine.
Step 6: Optional
You can polish resin when it has fully cured. I haven't gotten around to doing that but these pieces would look even better with a nice polish.
A metal or wood frame for the specimens is also an option I am working on.
Participated in the