Use of Sodium Hydroxide in 3D Printing Process?

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Colin Muir
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Use of Sodium Hydroxide in 3D Printing Process?

Post by Colin Muir »

We have recently started using a Projet 30 polyjet printer. Whilst we are very pleased with the resultant prints, part of the post-print cleaning process involves soaking the printed parts in diluted caustic soda (Sodium Hydroxide). I would be keen to by-pass the use of this hazardous material if at all possible. We have tried using simply soaking in water and this seems just as effective at swelling and loosening the support material prior to water jet cleaning.

Does anyone know the intended purpose of this chemical in the process? Is it to neutralise the pH of the print, or simply to swell the silicon support material? Objects that I've printed and cleaned only with water (both soaking and jet-washing) appear as clean as those cleaned with caustic soda. Presumably the extended soaking of parts in water would equalise their pH anyway?
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Re: Use of Sodium Hydroxide in 3D Printing Process?

Post by max72 »

Not sure about you printer, but with diy printers caustic soda is used with PLA support.
PLA weakens and gets brittle also with water if you give it enough time.
Caustic soda simply accelerates the process. Same applies with agitation tanks.
Do you have info on the support material? A datasheet or the MSDS?

Massimo
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Colin Muir
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Re: Use of Sodium Hydroxide in 3D Printing Process?

Post by Colin Muir »

Hi Massimo,
Thanks for the reply.

The support material is 'Fullcure 705', a translucent gel-like material similar to a semi-cured silicon. I gather from the MSDS (http://www.stratasys.com/~/media/Main/S ... 705-US.pdf) that its main components are Polyethylene glycol, Propylene glycol and Glycerin, also there is no mention in the data sheet of using sodium hydroxide as a clean up agent on contaminated surfaces.
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Re: Use of Sodium Hydroxide in 3D Printing Process?

Post by jvegher »

Hi Colin,

I just joined the group so pardon this late reply.

As a 3d printing service bureau, we've been running an Objet Eden 500v for about 7 years now. The sodium hydroxide bath is meant to help remove the support material from the parts. I'm very surprised you haven't noticed any difference in surface quality when you don't soak the parts.

The bath is a necessary part of our process as parts that aren't soaked for about an hour have a slight tackiness. Sometimes we need to double soak parts to eliminate it.

John Vegher
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