February 17, 2008

DTQ: What To Do About The Plastic Bottle Crisis?

It figures that just as we get back into the swing of the baby bottle phase, and we break out a new pack of the Playtex Ventaire bottles--in mix-and-match pastel colors--a new study comes oot of Canada showing that all the popular polycarbonate baby bottles still--STILL!--leach Bisphenol A. Just like they did this time last year.

So I've been thinking about it, and I'd like to do something to improve this unacceptable situation, which the Bottle Industrial Complex seems unwilling to address: I want to make some of the neck ring and base pieces for the Ventaire in some non-pastel colors. The wife's thinking of white, and I'd like a nice, silvery grey. The Macifier: a parent's best friend [see artist (sic) conception below.]


These components are injection-molded from polypropylene [PP], with threads and a ring of tiny gripper teeth on the inside. The base is also perforated, and a little silicon vent cover [patented, btw, oh wait, so's the whole assembly. let's come back to that].

epoxy_mold_tool.gifI guess replicating them entails making a mold [tooling?] and then producing a short run of them [10? 100? 500? 1000?]. There's a seam right on the edge, so the original mold may be like two nesting pieces [a last?], one for the outside and one for the inside?

The only reason I'm even considering this is because of the so-called rise of custom manufacturing and the computer-driven tools that have ushered in a new age of instant, cost-effective parts production. Only I'm not quite sure if we're there yet.

Do you scan these two 2-inch plastic pieces and 3-D print them in polypropylene? Because then I could just make a few. Do you scan them and make a more precise mold because ganking the tooling by casting from an original [is this called splashing?] invariably throws off the tolerances a bit?

Does the PP just come out looking like that, or is there another finishing step, or a plastic grade question I don't even know to ask?


As for creating new versions of someone's patented parts, if it's just for me, I frankly don't lose too much sleep over it. The aftermarket for car parts and accessories is huge, and long-established. If this ends up looking good--or if I end up having to make 500 rings to get the 4 I want. Though I'd probably cry about the B-school tuition gone to waste, I can't see any legal reason DT couldn't become the JC Whitney of the baby bottle industry. [Next up: stroller handle cats with turn signal eyes. And mud flaps.] More practically, is there some Secret Code of The Molders that means producing any of these things is out of the question?

I know you can do this while wearing Dockers, but can you do this on a stove? I don't have any Dockers, and I'd really rather not. Are there 496 other Ventaire users who want in on a set of white and silver rings?

Plastic baby bottles may pose danger [marketwatch]
Bisphenol A leaching from popular baby bottle [chej.org]
Sounds better in Quebecois: Des biberons toxique! [environmentaldefence.ca, which tested the Playtex bottles]
Epoxy molds yield production material prototypes [injection molding magazine]
eMachineShop: create real metal and plastic objects in a virtual machine shop! [emachineshop.com]

Previously: About that BOTTLE OF DEATH... 02/07

Related: If You Can't Buy It, Build It: Wanky the Safety Cat [jalopnik]


Rapid prototyping is probably not going to work. You can create PP parts using fused deposition modeling (FDM), but you are limited to their stock colors. You're also looking at ~$100 per part most likely. FDM parts have a fairly rough finish and are usually sanded and painted, but if you wanted to do that, you could just paint what you already have.

Your best bet would be to have a cheap aluminum tool made and mold them. The problem is, an internally threaded part like that requires a complicated multi-part mold, so it won't be cheap. And of course, all the cheap mold shops are in China. If you want to quote it, I would try mfg.com, which is like Ebay for manufacturing (it's awesome). For quoting purposes, you could probably get away with just posting some good pictures of the part. If it went to China, I wouldn't bother scanning it, just send the whole assembly and let them figure it out. I would imagine you'd be looking at a minimum tooling cost of $1000 per part (and maybe as much as $5000), but your per part cost would be pennies after that.

I think the best advice is this though: learn to love the pastels.

Just had another thought- you might be able to create a silicone mold off the original part and use that to cast a few parts. Because the silicone is flexible, it's forgiving of all those undercuts on the threads. Surface finish quality won't be great, and the mold will only last for a few parts, but that sounds like it might work for you.

My local baby boutique can't keep Evenflo glass bottles in stock. Oops, I cleaned out their last 14 bottles this weekend (good for freezing for storage, too).

Siliskin is a silicone cover nervous parents can use if they're worried about breakage of the already thick tempered safety glass.

Not saying this isn't a bit scary, but here's two things of note: first, in the study, they're leaving water in the bottle for 24 hours; and second, even in that time there wasn't significant leaching with room-temperature water -- only with it heated to 176° F. They say the heat simulates wear over time, which a referenced study says makes things worse, but I'm not sure the effect is the same. Plus, again, there's the 24 hours thing -- sounds like "don't leave liquids sitting in the bottle' is a reasonable mitigation strategy.

On the other side of things, they note that bisphenol A is more soluble in milk than water, which suggests to me that, uh, maybe they should repeat the study using milk instead of water.

[yeah, their explanation of the methodology left me with similar questions. When does the leaching occur: at high temperatures? AFTER high temperatures? The non-existent readings at room temperatures made me want to be sensible about not using scalding bottles, worn bottles, or day-old water or bottles. But otherwise, the best solution for us is still to change the color. -ed.]

Man, just buy the glass Evenflo bottles. Those are the only bottles my son has ever used. He drops them on (or flings them at) our wood floors with no breakage, they go in the dishwasher and the freezer, and there are no pastel colors.

Well another hot topic here!!!

With our son now nearly 3 we used Avent. Glad to hear that his refusal to take any bottle that wasn't straight from the fridge, kept him a bit safer.
Now that our daughter arrived Monday wee am... Was wondering if anybody had some better options to suggest? Or if we should just stick with what we know. Have some time as we subscribe to the "Breast is Best"-Policy {Greg insert your Uma Pic. if you feel the Urge}. TIA Sam

Have you checked out the adiri new bottles? I have been using Dr. Brown and hate them because there are too many parts and they leak. So I have been testing new bottles. I would be curious to know if anyone has had success with these. I think they are silicone.

Love the evenflo glass bottles too. Found out by chance that the bottles fit the Medela breast pump -- so you can pump directly into the bottle and then freeze (or refrigerate) for later use.

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