Acrylic desktop objects - how do they make 'em?

Factual Questions
1

A question came up at the office today, and, knowing as they do of my dallying on a questions message board, my colleagues asked me to ask you.

We were examining an acrylic desk, uh, object to display. It’s clear acrylic, with a 3D (not truly, just graphically) map, what appears to be a clear plastic strip with black lettering on it, and a company logo embedded. Dimensions are approximately 3/4" D x 4" W x 5" H.

While my colleague who possesses it described how the creating artisan had carefully mounted the 3D map at 2º off the plane of the obelisk, to create a lens effect enhancing the 3D imagery, on close inspection, no, Larry, you’re a good exploration geophysicist, and that’s why you say these things. The map appears just very slightly warped, as a piece of paper lying “flat” on water might.

The company logo appears to be more rigidly planar and the strip with lettering looks to be of the type one might get off of something like a Kroy lettering machine. It is mounted in a plane 90º away from that of the map and the logo.

While I’ve seen many metal objects (little metal baby drilling rigs and the like) embedded in acrylic cubes, spheres, etc., I never really wondered too much about 'em. But this one (and another popular in my biz - an acrylic with a perfect teardrop shaped airspace filled about halfway with oil) has me wondering.

Close inspection revealed no seams. I’m guessing that since heat would damage some of the embedded objects, and the teardrop airspace is otherwise a mystery, this must be a case of whipping up a cool slurry that can be slow poured into a mold, where it then sets.

But I don’t know that.

So OK, TM, how do they make these things?

2

There isn’t any heat involved in acrylic pouring. It’s a chemical compound that hardens after time, similar to epoxy.

My first guess on the teardrop oil is that the oil may have been frozen when the acrylic was poured.

3

It’s a resin mixed with a catylst. The stuff I used, about 25 years ago, was about as thick as syrup and crystal clear. It could be colored with transparent or opaque pigments.

In simple terms a plastic mold was filled to a certain level and allowed to start to set. Then the object to be embedded is added. It “sits” on the partly set layer. More resin is added and more objects may be placed as desired. Sometimes the objects were dipped in the resin before placement. This helped eliminate trapped air. Finally the mold is topped off with more resin. I usually colored the final pour to create a background.

After the plastic was fully hard, the mold is removed and any cleanup and polishing was done.

The oil thing could possibly be done by encapsulating the oil in a premade teardrop that had the same index of refraction as the cured liqued resin.

Here’s a source of materials http://www.eti-usa.com/consum/castresn/castresn.htm

4

I think the OP refers to a more particular class of objects, though it’s not clear. These paperweights (or whatever) can have obviously 3D patterns of little white points inside, that could be bubbles or burnt spots or something else. For example they might follow the outlines of shores and lattitude and longitude for a little globe, or they might show the exterior of a building, or of a little animal. I’ve marvelled at them in stores.
They couldn’t possibly place all those white bits as separate objects as they build up layers - it’d be hundreds of layers and thousands of objects.
I thought maybe they focus a laser to a point down inside solid plastic, and make little burns or blisters, under computer control. But that’s only a guess.
Hey, Ringo, did I understand or am I asking about something different?

5

I made a couple of these as a kid with left-over fiberglass resin, from when I was repairing my surfboard. It’s pretty straight-forward. You fill a mold half-way up, let it gel a bit, put in what you want, then fill it the rest of the way. I made them in dixie cups, then sanded them down to shape, but I’m sure they must have proper molds. They likely even have epoxy designed more to the needs of building these things. (The stuff I used wasn’t perfectly clear, and I’m sure different setup times would be better)

6

There certainly are a lot of these type of things on the market at the moment and your guess is spot on.

but the OP describes a little bubble of oil, which must be some kind of encapsulation…

I posted to this thread earlier, but the hamsters ate it; I’ve seen dandelion seedheads encased in solid acrylic - I can’t imagine even being able to immerse one in something as fluid as water without damaging it, so how do they do it with acrylic? How viscous is the acrylic when poured?

7

They’re probably sprayed very gently with multiple coats of adhesive first.

8

Napier

I believe those were covered in a previous thread. IIRC two lasers are used. Wherever the lasers intersect, they create a dot.

9

Thanks for the answers. I can see how surface tension might create the “warp” in the map when it was laid down on a viscous liquid surface.

Napier, no, I was speaking of a single plane map printed to represent a 3D view through perspective and coloring. My colleague Larry intercepted the ball and went for a 100 yard optics run. Balderdash.

Anyway, I’ve seen of what you speak, and I don’t know what the difference in making them is.

With the objects of the like of which I spoke, I am impressed with the absence of air bubbles.

I’m still curious about the oil drops. I’ll examine one tomorrow.