Make Architecture



#6 – Bulb Casting

*This project was a collaborative effort with JD Sassaman*

I will be covering the casting portion of our project processes. If you want to see more about the making of the molds we used, visit JD’s pages.

So, overall, we were interested in casting bulbs in different materials to create a collection of ‘bulbs’ that was a bit surprising. We were also looking to create a lighting piece that was interesting but also effective. An inspiration for this idea was the Rudy Grauman “85 Bulb Chandelier,” which uses an array of dimmable bulbs.

So with this idea, the big WHAT IF was around shading – what if this chandelier was a collection of bulbs made out of different materials, and what if it lit up without any ‘bulbs’ at all. Not only would this be comment on the shift towards CFLs and away from incandescent bulbs (soon an outmoded shape anyway), if we were to rig up a way for LED lights to be embedded in the cast bulbs, it would have a really great multi-color multi-material effect. SO this project is the first step in getting us towards the dream of each having an awesome chandelier in our homes…

All of our different molds

All of our different cast bulb products


use the proper protective gear at all times! This isn’t like spray paint fumes (which are bad, but which you can smell and be in control of…). I had a serious headache after using resin in the fume hood for just five or six minutes, and this is the low-VOC stuff! Be SUPER careful.

SO! let’s take a look at the different methods we used and their relative successes…

1.White Plastic 1

Material: Smooth-Cast 300 White Liquid Plastic (available at the art store)

Procedure: We cast the first two white plastic examples in the laterally cut OOMOO 30 mold. This white liquid plastic material siezes about six minutes after you begin to mix the two parts together, so have all your pieces ready to go before beginning the mix. We prepared the electrical cord in the proper spot on the bulb, secured the two halves together, and placed the whole apparatus back in a SOLO fratcup for stability and protection.

The material poured in quickly and hardened almost immediately. It became very HOT while we were doing the mixing, so it was good I was wearing gloves.

The only real problem with this cast was the fact that the mold had thinner and thicker edges to it, and thus the ‘thin’ wall of the mold wouldn’t generally keep its shape once we put everything into the SOLO cup. Which is to say, the two halves of the bulb have a ridge between them that could probably be sanded and smoothed to perfection.

2.White Plastic 2

Material: Alumilite Low Viscosity Super Light Liquid Casting Plastic

Procedure: Pretty much the same as the above, except this time we stripped the end of the electrical cord that is secured within the mold so that just in case of accidental appearance, it has an interesting effect on the surface of the cast.

This material, while mostly the same as the Smooth-Cast used in the first example, seems much more toxic. It made my eyes water, smells more powerful, and seizes up a bit more quickly. It’s also off-white, as opposed to the pure white white of the Smooth-Cast.

3.White Plastic 3

Material: A very ill-advised mix of Smooth-Cast 300 and Alumilite, the two materials used above.

Procedure: This was cast in the OOMOO 30 bowl half-mold. Our intention was to get the electrical cord stuck in one half, cast another half and then secure the two pieces together with glue or similar. We were finishing up a set of Smooth-Cast bottles, and found that the half-cast was only half-filled by the end of the material. We, figuring the chemicals were basically the same thing (btw: they’re not!) poured some of the Alumilite in. The 1:1 ratio of materials is also important here… if either of the chemicals is in excess, the cast will never dry and it will stay gooey and toxic. Which is what we have here.

Learned: Use only one product at a time. Make good measurements, or approximations of measurements.

4.White Plastic 4

Material: Alumilite Low Viscosity Super Light Liquid Casting Plastic

Procedure: We had three halves of bulb molds from our various attempts at the vacuformer (see JD Sassaman’s page for detailed explanation of that process). Because there was always a small flange on our molds where the vacuformer wasn’t able to draw the hot plastic directly to the edge of the bulb, we were curious what would happen if we clamped two halves together and poured material in, carefully rotating it so that it would only stick to the outside of the mold. This flange would eventually fill in in an orderly manner, we figured, and then we could file it off while the inside of the cast was still hollow and of an even depth.

SO… we greased up the vacuform molds with Vaseline (possibly not the best thing for this? Petroleum-based products don’t necessarily have a great relationship with other plastics… I might experiment with a, er, water-based lubricant in the future, as well as some of those more expensive ‘cast-release’ sprays and products available from Smooth-On at the art store.

The white plastic hardened within the mold and still won’t let go of it. It might have been a good idea to see what types of plastics the Smooth-Cast 300 bonds with and which ones it stays away from.

This was a fail, but I think it holds potential as a technique still because of the idea of making the cast hollow.

5. Rockite 1

Material: Rockite. Available at hardware stores in charmingly retro boxes. Just add water and it’ll harden in twelve minutes.

Procedure: This is a really nice cast. It’s a good weight, and the threading of the bulb comes out well. It was cast in the longitudinally cut OOMOO 30 mold and the shape is really smooth (none of that offsetting problem present with the laterally cut OOMOO 30 mold).

In this cast, the bulb is differently oriented than it is in some of our other casts… the small end of the bulb is facing down if the cup is right-side up. This means that the Rockite is poured through the bottom of the cup.

On this first Rockite try, we were so excited about the prospect of this working that we forgot to insert the electrical cord that it could hang from! Oopsers!

6. Rockite 2

Material: Rockite (with added water to help it enter the mold through a small channel)

Procedure: The Rockite was mixed quickly, and poured quickly, but the addition of the electrical cord into the construction in this instance meant that there was even less space for the Rockite to enter the mold through the small end of the bulb. You can see how goopily the Rockite attached itself to the cord on its way down into the mold, deceiving us that the mold was already full.

We’d recommend using a slightly more watery solution to aid in the pouring of casts, and so this doesn’t accidentally happen to you!

7. OOMOO 30 1

Material: OOMOO 30 for a cast, not a mold (how novel!)

Procedure: We had two half-casts from the vacuformer (see above and JD Sassaman’s page) and decided to experiment with how you might secure two half-casts of OOMOO rubber together.

We poured first one half (without the electrical cord) and then the second half, trying with the second to get the two to bond together ‘naturally’ since they’re both OOMOO 30. This was only sort of successful in the first attempt because of the flanges on the sides of the mold. For this example, we used the least-successful of the vacuform molds (which we had earlier rejected for use in our hollow white-plastic failure (see above).

While the two halves are very well formed, their connection is light and delicate, and we are afraid to trim the flanges too much, since that’s the only place that the halves are attached.

8. OOMOO 30 2

Material: OOMOO 30

Procedure: The procedure for this attempt is largely the same as the above OOMOO 30 example, except for a couple of very important details.

1. we greased up the vacuform mold with vaseline prior to casting.

2. the vacuform halves that we used were much higher in resolution than the other halves above (a better vacuform procedure)

3. the connection between the two halves was very intentionally done – they are well connected and there is hardly any flange between them because of the higher quality of this mold and because of the attention to the fusing process.

9. Resin 1

Material: Castin’ Craft Clear Liquid Plastic Casting Resin, stock no. 00191

Procedure: We used the laterally cut OOMOO 30 mold for this adventure, stripping the electrical wire from which the bulbs hang before they were inserted, since we knew they’d show up here more than in any other mold. The mold was in the SOLO cup that had been giving it its structure throughout all the previous trials.

We of course wore protective gear, since resin, even in its low-VOC forms, is nasty stuff. This included special silver gloves, a lab coat, goggles, and a face mask (the face mask, of the sanding-wood variety doesn’t protect you from the resin fumes, but i just didn’t want any nasty stuff splashing on me, and it’s better safe than sorry, no?)

So we mixed up the resin (using about ten drops of catalyst for five ounces of resin – NOTE: THIS IS A MISTAKE), and waited about two days…

I noticed after about four hours that while our resin was still liquidy, the plastic cup that I had used to mix it in was disintegrating, and fast! The SOLO cup was turning into a melty kind of goopy plastic, and the red dye in it, was spreading to the white parts of this!

Because I couldn’t do anything to save the cast that was in the works, I just put another cup under the one I had and figured that would take care of things…

After two days I demolded and found that either the resin had shrunk in the process, or I had incorrectly estimated that the mold was full. Either way, I decided that I would pour another layer of resin on top of this. Also, I noticed that the flange where the two halves of the mold come together was reddish and that there was a noticeable pink tinge throughout the bottom half of the still-sticky resin cast.

I poured another layer of resin to the top, this time using about thirty drops of catalyst for four ounces of resin. This part cured in about three hours (SO much better!), and wasn’t sticky or delicate to the touch. The directions say that adding more catalyst makes your mold more brittle, which would be a concern if we had small parts or thin layers, but since our bulb is a solid item, I decided that in the next iteration, I would go to town with the catalyst… and I did.

10. Resin 2

Material: Castin’ Craft Clear Liquid Plastic Casting Resin, stock no. 00191

Procedure: Wear lots of protective gear, mix it up, pour it in, wait, open up, delight in successes.

This iteration of the resin mold really takes to heart what we learned about catalyst in the last example. To say we used many drops is an understatement, we used about half a little bottle of it… maybe 150-300 drops? Quite a lot, was the measurement.

The extreme amount of catalyst in this test meant that the bulb was good to go in about two hours, with great impressions from the mold. It is, however YELLOWED~ a consequence of the catalyst, I assume. It’s also a bit more brittle, or so I’ve been told, as a result, but this is not a problem for us.

Once again, we used the laterally cut OOMOO 30 mold for this test, and it worked well, except that there is a small flange edge around where the two halves of the mold come together. A good test of this would be in the longitudinally top-cut mold, since that’s got a different way of coming together and securing itself.

So we’re not entirely there yet, but we’re getting closer to our stated goal of hanging these bulb-shaped objects together into a type of chandelier:

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Instructor: Nick Gelpi TA: Skylar Tibbits TA: Varvara Toulkeridou
Class Times, Monday, 1-4pm - room 5-216
4.184 is an intensive introduction to methods of making explored through a wide range of brief but focused 1-week exercises. We'll engage the real and leave behind representation in the focused context of this class gaining skills for utilizing a range of fabrication machines and technologies from lasercutting, waterjet, 3D printing, welding, formworking-molding, casting, gears, joints and composites.
In this workshop we'll constrain ourselves to the territory of the 1:1. Students will represent architectural constructions at full scale and develop a more intimate relationship with technology by engaging the tools and techniques that empower us. We will gain access to the most cutting edge machines and technologies in the MARS lab at the Center for Bits and Atoms.
The second layer of information for this course will be to look at a series of case studies in which construction methods and technologies have played a dominant role in the design process .
Over the past 20 years, architects have focused on the technology of representation to create new ideas of what architecture could be. Looking back today, much of that research failed to substantially change the way we design buildings by focusing on apriori formal configurations. This class makes the contention that this failure comes from a lack of considerations of the potentials within fabrication knowledge. We look to the future of what building might become, given the expanded palette of personalize-able technologies available to us as architects. Students will participate in curious technological and material investigations, to discover the potentials, known and unknown, for these various technologies.
The sub-disciplines of what's drawn and what's built have been compartmentalized and disassociated as the representational tools of architecture have distanced themselves from the techniques of making. At the same time the technologies for “making” in architecture have provided us with new possibilities for reinventing how we translate into reality, the immaterial representations of architecture.


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