Shapeways models as masters for molds for fine porcelain

Unfortunately this project has been cancelled due to unforeseen circumstances

Hi Guys,

Over the last 3 weeks or so I have been creating some designs to be 3D printed in plastic (white strong and flexible polished, and for smaller items Frosted Ultra Detail), with a view to having molds made of them for production in fine porcelain. Some pieces are designed for Jasperware and some sculptural forms too.

I am just waiting on a couple of Shapeways prints to arrive so I can be sure that the level of detail and finish are going to be suitable for molding for super smooth fine porcelain.

1.FUD should be good for jewellery sized objects, and the small plate design below. FUD will also achieve the delicate detail that porcelain can achieve (there is almost no minimum thickness for porcelain - extremely lacelike details can be produced)

2. I am hoping that WSF polished will suit a fractal lithophane/ LED candle holder.

3. Id love to create something lamp sized but WSF polished is only available up to a maximum bounding box of 150x150x150 mm, and FUD is going to be out of my current budget for very large objects.
So does anyone have suggestions on how to smooth large models in White Strong and Flexible? (complex shapes so I cant just sand it etc)

Below are some images of designs that I had intended to produce in fine porcelain. The porcelain manufacturer George Engel (Phoenix Rising Ceramics), provided colour suggestions by emailing me several roughly (photoshopped) variations of my original designs (some shown below).


Janelle

Hi Janelle,
I'd find a clear acrylic coating (spray) that won't attack the WSF. It will probably take many coats to smooth things out but it should work ehh?
-G

Hi Glen,

Thanks very much for the suggestion it would make it smoother, and less porous on the surface, but I think it might reduce the detail in the fractal parts. I suppose it would depend on how detail my piece was and to make sure I did very light coats of the acrylic.

Janelle

Hi J,
One way or the other you will loose detail if you either build up or take down the as printed surface. Why don't you print it with the FUD material? Costs more sure, but it might give you what you want with less hand work.
-G

Hi Again,
Oh, I see a mold for the lightning element! Actually I think you would not be able to make a suitable "mold" of this design for slip casting porcelain. To many undercuts! I think molds for casting clay slips are usually made from plaster. This aids in drawing the moisture out of the clay slip. I believe this is the same for porcelain. So these would be rigid molds and any undercuts will interfere with getting the model out of the master mold. Back to the drawing board?

-G

Hard mould is the classic tech. New methods use silicone, like resin castings in model making world, which allows some level of undercuts. Someone was advertising his company around here... wait, the link is in the first post. ^_^ Maybe the fractal "roughness" is too much even for silicone, it depends, you could always do some DIY tests first. Things could get stuck and tear the mould or the part, or bubbles appear and give extra material in the wrong place (pro systems use vacuum, so bubbling is minor or zero).

About smoothing, any brushable acrylic varnish, bought from any art shop. They are normally white liquids that dry clear, some even have UV protection. WSF drinks them, and you can pick different grades, from matt to satin to gloss, and combine them in layers if you want the filling properties of one type with the specularity of another. They are also water soluble, so coats can be applied thinner to increase control. It would take more time than spraying, but will ensure you get as thick as you want, and in the places you want.

Hi Glen,

The porcelain manufacturer (mentioned above) told me he has a proprietary technique for rubber molded ceramic and porcelain - an welcomes undercuts designs.

Janelle

Hi Stannum,
Thanks for the extra info on varnishing - it sounds like that is the way to go with my WSF / WSF polished models

Janelle

Two great products that can be sprayed on and provide a smooth finish but not add materails or loss of details like varnish or acrylic spray can do. We use these for glass casting and moulds for kilns.

BN Aerosol
Boron Nitride based, white aerosol spray with an alcohol/acetone binder system. Resistance to molten metals, high temperature lubrication, electrical insulation, high thermal conductivity, resistance to molten salts, resistance to molten glasses, release agent for ceramic hot-pressing.

White Silk
ZYP Coatings' WHITE SILK BORON NITRIDE allows an inexpensive, thin boron nitride layer to act as a barrier to prevent diamond matrix or metal bond powder from sticking to graphite molds and plungers/punches at temperatures above 850 C.

Thanks erckgillis for the finishing suggestions! I'lll have a look and see if I can obtain these products in Australia. It would be great to use something that didn't cause loss of detail.
Janelle

Hi Janelle,
Boron nitride (BN) coatings are used to coat the surfaces of hot molds or any surface that needs resistance to hi temp molten materials. Meaning surfaces intended to to be in contact with molten metals, salts, glass etc. I'm not sure it would be of any use for slip casting porcelain into rubber/silicone molds. Don't get me wrong, BN products work like magic to prevent hot glass or metal from sticking to molds and things, but it seems like your priority is smoothing your master models so a nice clean rubberized mold can be made from it? I think only two choices remain, both are a pain in the butt! Either, -A- hand finish/polish the surfaces or, -B- apply coatings to fill and smooth the surface. I know you have the touch to make this work Janelle .
-G

Hi Janelle,
Interesting what you're trying to do and although I can't recommend a product to finish WSF so that it's suitable for making moulds, there may be another way!

Have you considered making the rubber mould by printing the mould on an Objet 3D printer using one of their tango (rubber) materials? info here.

Or using an Objet Connex printer which has multi material capability so you could adjust the stiffness of the rubber. info here.

I'm not sure how the printed rubber would react to the porcelain, but I wouldn't imagine the porcelain would effect it. You could get some small test pieces made to try it out before investing in a full mould. Also the resolution and surface finish is much higher from an Objet machine, than for WSF.

So as you're producing the mould directly via 3D printing there should be minimal loss of detail once the porcelain is cast, and if you've got the property of the rubber correct it should pull away from the porcelain once the porcelain has dried out, ready for firing.

The only down side is that Shapeways don't yet offer the rubber material, but you could contact Objet directly or an agent and ask them the question!

Good luck with this and let me know how you get on.

Mark.

Thanks electrobloom for your printed rubber mold suggestion - that's something that I hadn't considered at all - could be useful for future projects!
Thanks Glen for your comments too - so you don't think that I could use something like th BN products for smoothing? - I've never tried them before.

I wouldnt mind having something that could give the heart fractal plate a bit more shine but I'm a little hesitant as I don't want to mess the model up. I'll check with PR ceramics if the WSF polished model is OK without a coating for their process.

Here is my progress on the Fractal peaks LED candle holder.
George Engel from Phoenix rising ceramics suggested that I could try coating my model with 'crazy glue (cyanoacrylate) and coat the surface, then sand it with finer and finer sandpapers.' It called 'super glue' here in Australia . So here are the results after 3 coats ( on the fractal part only).
I did it outside on the balcony (really strong fumes) and used latex gloves so I didn't adhere myself to the model or stick my fingers together.

The base is in white strong and flexible polished - I haven't coated it with anything yet. The 'fractal peaks' part was produced in White strong and flexible (Shapeways kindly advised me that it couldn't be polished in their machine because the points would break off).

I put pictures on Shapeways here also (model page).
https://www.shapeways.com/model/356650/fractal_peaks_led_cand le_holder.html?key=e1cfd2e4d8c57eceaa042abc9da72fe2

Here is an image and link to the model page for the 'White strong and flexible polished' Heart Candy dish.

https://www.shapeways.com/model/356745/fractal_heart_candy_di sh.html?key=6cdf4ded21501bca7d54608aa21569fb

Hi again,
BN has the consistency of talcum powder. It is very soft and chalky. It's not designed for your application here, it might even interfere with mold rubbers and it's also rather expensive.
Because of the tight and intricate surface of your fractal designs I see no way of sanding or polishing to an even finish. At best you will just be hitting the high points and if you go to far, detail will be lost. So, what is needed is an easily applied filler material that will fill in and bridge the tiny gaps between prominent features. You want something with a reasonably high build rate but not so thick that it will drown out surface features completely. CA glues, aka Super Glue works really well but you have already discovered it's drawbacks. Also because it is clear it makes it hard to know when enough is enough. The nice thing about CA's is that they cure to a hard surface which sands/polishes very nicely. So it's great for broad, essentially flat and smooth surfaces. But since your surfaces are anything but flat and smooth CA might be overkill. If you have already used it, then let er rip, as is, forget trying to sand it.
I think plain old "red"auto body primer (spray) would also work as a base coat to seal up the micro pores of your plastic prints. It goes on easily, is opaque and dries to a flat finish which makes it easy to see when enough has been applied. The primer could be followed by a clear coat of polyurethane (spray) which would leave a near mirror finish with NO sanding required. Presto, ready to pull a mold. Cost you about $10 for materials.
-G

Some brands already sell colored CA. For example http://www.filla-glu.com/page_1975304.html

Plenty of hard coat spray on materials not just BN powders. Many have smooth, glossy or high temp finishes good for molds and other ceramic applications.

Depending on the final finish you may consider sprays, paints or coatings to protect your fine details and or as a surface prep for other finishes...

Example-

http://www.zypcoatings.com/Datasheets/BnHardcoat/BnHardcoat. htm

Z-Guard
Produces a hard, abrasion and chemical resistant zirconia (ZrO2) coating that is protective to all ceramic bodies against most molten metals and corrosive environments to above 3200 F (1800 C). Z-GUARD may be applied to soft or fibrous structures with no special rigidizer to produce a more wear resistant surface layer which is also resistant to most high temperature reactions which may degrade the ceramic.

Also check out some of the other materials depending on if you want a hard coat, glossy or other prep for challenging materials, spray on, paint or other coatings just PM me for any details or questions.

Titanium Nitride
Yttrium Oxide
Zirconium Oxide...more

Thanks Glen for the autoprimer and polyurethane (spray) suggestion. I'll try to buy these locally today and test them for finishing, and thanks Stannum for the coloured CA tip - this will help in future models to see how thick the coating is.
By the way regarding CA, there were a couple of little mistakes (unwanted dents I hadn't noticed in my fractal during the computer modelling process) , so I filed off some powder of white strong and flexible (from one of my models that I managed to break) and mixed it with the CA - it worked as a filler.

Erckgillis those Z-Guard products sound like they could be very useful for specific purposes...I don't need any heat resistance or special properties though because the molding process that the manufacturer is using isn't using heat. My master models pictured are in laser sintered nylon (white strong and flexible), and making them smooth and as shiny as possible is my aim, because the texture of the model will be reflected exactly in the finish of the final porcelain.
Are the z-guard products more geared towards coating the finished porcelain piece, e.g if I designed a candle holder that was not just for L.E.D candles. Also are there any of the coatings that could make an item food-safe (as an alternative to glazing the porcelain/ceramic surface).

Janelle

Hi All,

I painted the base for my model with grey colored auto body primer spray - thanks Glen . It worked well - it shows the texture that still exists in 'White strong and flexible polished.'
I then coated it far to heavily with polyurethane spray ...ooops, drip marks every where. So I have now removed my heavy handed work with acetone. At least nothing I have applied to the model has seemed to react with or deteriorate the original model.
Next week when i have a chance I'll sand the model base back to being smooth and then spray lightly to achieve a shiny surface.

Janelle

Hi Again,

I had more success with the fractal part of the model...and believe this part is finished now. In addition to the CA (crazy glue/ super glue) that I had already coated it with I added a layer of clear auto spray. It has taken out a little of the detail but it is smoother and shiny which is the main aim.
This model because of its detailed and busy nature is a bit easier to lacquer than a really flat one (given my predisposition towards adding too much lacquer etc).



http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_2.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_3.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_4.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_5.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_6.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_7.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_8.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_9.jpg

http://unellenu.com/images/stories/3D_fractal_peaks/fractalp eaks_lacquered_more_10.jpg