Lost Wax Casting

This is a brief outline of my lost wax casting technique. There are several ways to cast, this is just the way I do it as a one woman show!

You can view a lot of my finished work at http://bcyrjewelry.etsy.com

To see more tips, techniques and musings check out my blog - http://bcyrjewelry.blogspot.com

I use all sorts of random tools for my wax working. Most importantly, my fingers, and a tiny needle in the end of a pencil! I also made a little denatured alcohol lamp out of a baby food jar. The wax I use most of the time is a soft brown wax. Its my favorite.

Step 1 Wax work 1

The beginning of one of my flowers

Comments

[Ozzynny]

Hello and thanks for this share. I haven't had much experience with casting, but am. About to try and cast some rings using the soft brown wax that you love so much :) Before this I had used the hard carvingwax a few times. Can you tell me how thin is too thin? The theme we are working with it to "give volume to a ring" so there has been folding, hammerng and milling. I have a few quite thin areas because i wanted to avoid a50gram ring :)

Thanks for any advice you can offer!

[bcyrjewelry]

Hi there! I'm so sorry for just seeing this - you've probably cast already?

It really depends on the metal that you're using as well as what areas might be thin, so it is a little hard to just give a simple answer. I personally wouldn't go below 18g (1mm) for sterling, although some areas could be thinner. My rings are usually between 1.5 - 2mm. If there are some thicker areas and some thinner areas, you can make sure to sprue appropriately to make sure the metal casts all the way. so if you have a thicker band and some small thinner details on top, that would cast fine as opposed to a thin band and even thinner details.

[snowluck2345]

I'm interested in how you vacuum the metal in. Is there a hole in the bottom of you plaster mold and you put that hole over the vacuum peice?

[bcyrjewelry]

Hi there!
No, there is no hole in the mold. Some people use a wax web around the inside of the flask - so when the wax burns out there is a web of holes that allows the vacuum to pull better. i think that may be useful for larger flasks... i use pretty small flasks and the wax webs just weren't worth it for me. The vacuum just creates suction and slight porousness of the investment is enough. I'm always kind of amazed that it works!

If the investment didn't set up properly or there was not enough investment between the negative space of whatever you're casting and the top, the vacuum can pull a chunk off the mold. It is important to leave about 1/8" at the top of the flask, allows for better pull.

hope that helps?

[snowluck2345]

I think it makes sense now. The vacuum pulls the metal into all the pores of the investment, by pulling the air out.

[spark master]

I have not cast anything since grammar school when I made 1 sided lead quarters and passed them to the NUN who was my teacher, (she was highly impressed, cause I recieved neither punishment or wupp'n). I have heard of centrifuge machines , but cacuum?

I are beez confuzzled, you make the mold using wax positive and some kind of plaster (investment?). I understand you suck the air out of the plaster while it is wet, then bake out the "wax" , but how does one get a vacuum to stay that way when you pour in molten silver? or does one do it real fast and then bell jar it and suck air? The mold being so hot the metal does not solidify while you pour, ALLOWING the bell jar to be used with vacuum, after the monolithis pour, (no dribs and drabs)?

sorry if I am too dense for this. I want to cast a few simple shapes out of silver soon and this looks cool. May I also ask does "investment" material have less of a "shrinkage", Or none perhaps when compared to plaster of paris?

I think I need a primer on this !

[bcyrjewelry]

hey there!
The vacuum for the casting part does not actually use the bell jar. The vacuum has a toggle switch that changes where the vacuum pump pulls from - for investing it is through the bell jar and for casting it is through the table. If you look at the image #15 - right above my hand you can see the hole in the rubber mat and table. The vacuum creates suction through the investment and pulls the metal in to the fine details once the pump is turned on (it is actually turned in before the metal is poured b/c yes, the metal cools extremely quickly)

There is a tiny bit of shrinkage, though not very much.

[spark master]

I will definitely recheck it all out, since I would think th evacuum would suck liquid metal into the vacuum bore and chamber below (the pump). no?

Is the vacuum system good for casting liquid resin and epoxy goops as well? I know all the non understanding on my part is due to total lack of knowlege.But I would like to make a few item and any info I read first will help in the end.

thanks

[bcyrjewelry]

i totally missed this! I'm not sure about casting other things... I think it would really depend on the mold maybe?

[finbar galdeep]

Awesome instructable, but what sort of investment do you use, and if you didn't have a kiln but stuck it in an oven on high, (around 5 hundred or on the self clean thing) for a while would it work to cure the investment, or would it depend on the investment. also could you use paraffin wax

[bcyrjewelry]

hey there! I use an investment called 'satin cast' by kerr - it is specifically for jewelry casting and gives amazing detail (down to a finger print!) it also is designed to take the extreme temperatures of the kiln.

I would definitely not use a regular oven for a couple reasons - one is that I usually burn out up to 1300 degrees. For the investment I use, the kiln needs to get much hotter than 500 - sometimes it only goes up to 1150 if I'm casting stones in place.
There might be types of investment that are formulated to cure properly at lower temperatures? I've never looked in to it.

The other thing is that the wax fumes are pretty toxic and I wouldn't want the wax burning out in an oven that was in a house or would be used for food.

You can use any kind of wax and even burn out natural materials and some plastics. (again, that can be pretty toxic too) I have friends who experiment with all kinds of things - some work and some don't.

hope that helps!?

[trueblackdragon]

if your using wax not plastics! you can also pre burnout your waxes with steam to remove maybe 95% of the wax! less wax means less toxic fumes.
Chris: [e-mail] Owner Mad Scientist's Laboratories & Cavender & Kin Jewelers

OOps! also if you want to reproduce almost anything plastic in metal IE: tin or plastic soldiers, you can sprue them up and gate them for better flow but you will need a high temp burnout!

[Bugsley]

This is fascinating, excellent Instructale. Lots of great details.
Bravo!!

[Ichmawida]

i really want to try this! haha
It seems that those Tables are kinda expensive? Do you really need one like this or can you use an vacuum former used for plastic or a bell jar? also where did you get yours?
thanks :)

[mnpazan]

Very informative! Thanks!

How do you create a seal between the vacuum table/machine and the flask during casting? Looks like maybe a special gasket of some kind, is that right? It looks like there are rings burnt in the surface from previous castings, implying that it might be something that wears out with repeated use and gets replaced. If so, can the gasket be purchased separate from the device?

I have a vacuum setup for resin casting, and it would be super simple to DIY a benchtop unit like that for use with the same pump, if I could figure out or source a seal that could take that kind of heat.

[jisaku]

Is there any way to do this without a kiln?

[bcyrjewelry]

i'm not sure about doing lost wax casting w/o a kiln - the investment needs to 'cure' and the wax needs to melt out. there are definitely ways of casting that don't require a kiln. There is cuttlefish casting and sand casting (which i've only done large scale, but i imagine the principle is the same - I have a few friends that do it a lot) With cuttlefish casting, you prepare the cuttlefish and actually pour the metal in to it - it's a one time shot, but no kiln! there may be a tutorial about it on here?

[Wazzupdoc]

The magazine "Backwoodsman" had an article on cuttle fish bone casting a few years ago. If you google the mag they might have an article index.

[jisaku]

ok, thank you

[heathbar64]

Very informative. One thing I didn't understand was about the vacuum. I could see when you were vacuuming out the bubbles under the glass dome ok, but how did you use the vacuum during the actual pour of the metal?  Also, what type of material is it that is used for the investment?

[yoyology]

This is making me nostalgic.  I loved casting in my jewelry class at college.  Made a miniature rifle for a friend using brass tubes cast in place in an aluminum stock.  My favorite piece, though, was a sterling ring covered in little mushrooms.  I used a hot iron to melt drops of wax that I dropped into cold water.  The hardened droplets looked like mushroom caps.  Then I rolled tiny stems, attached them to the caps, and "planted" them in a ring form on the mandrel.

We used a vibrating table and centrifugal caster.  I ended up with a few bubbles in between the stems, but they looked like puffballs.  :-)

[mlcorson]

I've only done lost wax a couple of times. In class on a centrifugal machine and once at home with my vacuum. Which one do you think is better? More flexible or more forgiving? I have a dismantled centrifugal machine, but I never liked the idea of spinning molten metal around my workshop.
-m

[mlcorson]

This is one of the best descriptions for the vacuum lost wax method I've seen. The one handed torch set up.. brilliant.   Great work! I've tried this before. Both with vacuum and centrifugal methods. A critical mistake I made was not having enough space at the top (then bottom) of the flask. One time, the vacuum pulled loose investment into its filter and hoses. How do you avoid that problem? Do you have a filter or something on your vacuum?

[bcyrjewelry]

oh thank you! i've actually been meaning to update it too w/ some more details and better photos.

unfortunately, I have no tip on having the investment go in to the table/hoses etc... and am quite fearful of that happening! well, more terrified of having the metal go straight through... the only time i had the top of the investment come off was a HUGE wax that i knew was risky and only had about 1/4" of investment above the wax. I would say just make sure that there is plenty of investment above the piece. I normally have between 1/2 and 3/4" above the wax - particularly if the wax is large and creates a large open area.

[mr. clean]

wow incredible work!!!

[cripty]

beautiful work, i use to sell dental supplies and got all my equipment for free (slightly used).  very fun.  great photography.

[EMC45]

Cool.

 

[Re-design]

Excellent inst. Beautiful work. Envious as an artist wanabe!

[blindpig]

Have you considered "steam casting" as an inexpensive alternative to vacuum casting? It is a more primitive method but requires less expensive equipment. Might be considered for experimental lost wax casting trials. Would allow trying the process without buying equipment first. Adding equipment later always an option.

[ampeyro]

I'm trying to make a lamp that uses LEDs, and they need a heat sync that fits in the lamp's design, do you think that I could use the same system you used?, the heat sync will be made of aluminum

[bigmacdaddy]

I have been wanting to begin working with the lost wax method for some sculptures. Than you for your clear directions and tips. I can see that the vacuum apparatus is essential. Also, what kind of gas are you using to heat your metal? You may have mentioned, but I couldn't see the type of gas. I have used a turbo torch with propane to melt silver,

[Cthulu]

Your amazing hahaha. Great Work!

[bcyrjewelry]

aww, thanks! :)

[hg341]

wow i liked this a lot although i have never done this befor i do know a few things A) you dont need to the vac table(i do want one though) you can use a vibrating one B) where do you get your filler the "investment" and C)how would you make casting sand

[OldOwlIronworks]

I like it...I Swordsmith but I need a way to make fittings and mounts for my swords. they probably wont have much detail, but i dont really care. is it totally necessary to have a vacuum? if so how much is one? thanks(:

[bcyrjewelry]

ooohhh swords. I always thought i'd make swords some day. the vacuum set up i got was about $650. w/o vacuuming the investment - you can be left w/ big air bubbles - which turn in to nice little metal balls all over your piece! not using the vacuum when casting (uh, i know by mistake) the general form is there, but there is some loss of detail. it looked a little 'melty'. and you run the risk of not having a complete casting. when i did larger metal casting - I did sand molds - and the molten metal (iron, bronze or aluminium) just got poured in and that was fine. I haven't done any in a long time though so its all real foggy. This method is what I use all the time - it works, so I just stick with it!

[OldOwlIronworks]

couldn't the metal spheres be sanded off? the sword fittings aren't going to be the greatest ever. I built a forge for blacksmithing:
http://www.instructables.com/id/2_day_20_50_Blacksmithing_Forge/

what is the process of sand molding? do you know if I can use brass?

thanks so much!

[seeem]

Nice :D

[stayputnik]

Agreed... great instructable. Looks like lots of fun!

[uguy]

Well done ible and nice looking jewelry, web site is very nice as well. Good job, thanks for sharing.