Seal a print?

I have a DLP SLA printer and have designed a specific mouthpiece for a musical instrument like a recorder or whistle.

However, all of the resin manufactures I have emailed say their resin (even when cured) is not food safe and should never be put in the mouth.

Is there something I could dip the mouthpiece in (or at least the part that will be in the mouth) to completely seal it and make is safe to put in the mouth?

I see that there are polyurethanes to seal wood, would that work? Or maybe a quick dip into silicone..?

How about making silicon molds from your print then casting that in a resin that is safer? I've only done very basic silicon molds, and not very well at that, but I think with some practice and the right equipment this would also allow you to make a better end product.

https://youtu.be/iRj6xzNx7P4 looks like a nice video showing the process. I'm guessing a mouth piece would need to be done in 2 parts due to the internal structure.

Poly for wood is NOT food safe. The only truly food safe wood finish is a Mineral oil and beeswax blend.

Silicone will not hold up as a mouthpiece. The outer layer would have to be too thin to make the piece usable, and it would wear down too quickly.

They do make a food safe Epoxy resin. Make a mold and cast your mouth piece in that.

silicone would not be for the mouth piece. it is a flexible mold material. You cast in resin. See the video. ;)

I do Silicone molds myself. I know what YOU meant. The OP asked if dipping it in silicone would be a good idea.

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Originally Posted by Marm

I do Silicone molds myself. I know what YOU meant. The OP asked if dipping it in silicone would be a good idea.

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Oops. Yep, you are correct. I guess I skimmed over his dipping idea.

You can either have it printed in foodsafe PLA on an FDM printer, Shapeways ceramic is foodsafe as well which can be a nice option. Otherwise use your SLA printer for a mother model and create food grade epoxy castings from a silicone mold, as Marm suggested.

If you could find the resin used by Invisalign, then you would have a product that has been certified for oral applications. They SLA customised dental retainers for correcting your teeth, and have established a successful business.

http://www.invisalign.co.uk/en/Pages/Home.aspx

Rich

Thanks for the info guys!

Making a mold would be very difficult. This specialty mouthpiece has several air passages instead of one (think: cooling passages for a car engine). I would have to re-design it to anticipate each air passage being cut in half for a mold. Not impossible, but would have to start all over.

If I was able to actually make a mold, the material I would like to cast would need to be very hard and dense, like delrin/acetone. Is delrin castable? Or is there something similar?

I'm hoping to do everything in-house as much as possible.

Finding non-toxic resin would be ideal, but so far I have no found any. Dipping just the part that will be in your mouth in some food-safe non-toxic sealer would also work if it is hard. Marm is correct: teeth would quickly tear through the silicone coating. Hmm.. Maybe heat-shrink?

Check out smooth-on, they make a variety of mold and casting materials.

Molded pieces can be cast in 1 piece, they don't have to be split in half.

Here's a link to a video where a fellow turner is making food safe tankards, and using food safe epoxy to line them: https://www.youtube.com/watch?v=ok2oQVK-F3g&t=7s There's a link in the description to the epoxy. And I get about 32,00 results, most of which are applicable, to a google search.

I've chewed through more SCUBA mouthpieces than I can count. If it's a soft rubbery material on top of a hard plastic, it will fail. And the glues in standard heat shrink are pretty toxic if swallowed. I've never seen dual material mouthpieces for anything I can think of. It's either designed to bust some teeth if chewed on and last forever, or it's designed to be soft, replaceable, and eventually fail. For a musical instrument, which requires specific airflow patterns, and the repetition over a long time period of those patterns, you should probably make a bust-a-tooth style mouthpiece.

Delrin (POM) is very moldable - even as thin as 0.4mm walls are possible.Also check out the Formlabs dental and ceramic resins: https://formlabs.com/materials/

Google Denture repair epoxy