Wax For Masters

[mark poulson]

Has anyone here run across the sculpting wax that jewelers use in their lost wax casting process?

It seems to me it would let me skip a step when making a mold, and let me cast my master in hard mold material without having to worry about undercuts and details.

As it is now, the only way I can get a rigid mold, which I like, is to either use someone else's soft plastic as a master, or make my own with Sculpey clay, make an RTV silicone mold, and then pour enough soft plastics to make a multiple cavity mold.

[wchilton]

I've played with it, but not a lot since most of my molds are silicone. Here's what I know. First, found an on-line source at "http://www.ottofrei.com". The wax I bought (years ago) is casting wax and it is really hard. Almost like plastic. That's actually a good thing if you want to carve it since it maintains it's shape. Many of these waxes are formulated to minimize shrinkage during cooling. They also have a fairly distinct melting point, so if you try to heat a model to get the finish to smooth out it's real easy to melt the whole thing. Also, when they do melt, they are very liquid so they run/drip. For these hard waxes, you're probably going to have to heat up your hard mold to get the models out and the models will not be re-usable.

I've also had some success using regular hot-melt glue for models. This was for silicone molds, the stuff might stick to POP if you heat it enough to melt it. However, hot melt glue gets soft and flexible before it melts. You could probably use hot melt glue with POP if you sprayed it with silicone release agent before pouring the POP and then don't heat the mold enough to melt the hot melt but just enough to make it soft for removal. Forget about ever trying to carve hot-melt...it's too gooey.

I haven't tried either of these to make a POP mold. Would recommend a quick test with single model to work the kinks out of the process before trying a multi-cavity mold.

[mark poulson]

Thanks for the info, and the link. I'll check it out.

What type of wax did you buy?

[quietfly]

I've considered it and have even started experimenting with it. The issue i see with multiple cavity molds is needing multiple exact replica's. for this won't you always need to make atleast one single cavity mold?

[mark poulson]

The way I figure it in my squirrely little mind, if I make one master, and one hard mold, I can pour enough soft plastic duplicates to make more cavities.

I am thinking of using Pour Rock for my molds, since it's cheap, fine grained, hard, strong, and doesn't shrink. Once it's cured out, it should work fine. I'll probably seal it with something before I pour, but I'm not going to spend all that money for RTV if I can avoid it.

[atijigs]

Used it for years making crowns. As previously mentioned it is hard. Can be carved in very fine detail. For the finishing we used to use an alcohol torch that had a sqeeze bottle. By sqeezing the bottle you would get a very precise burst of flame. With a little practice you can get it fairly smooth this way. The next step to get a mirrow finish would be using a small piece of nylon(as in stockings) and gently rub the surface. It's not cheap but for your purpose you can reuse it when you are done. I used to order it in blocks. I would think you can get it from any dental lab supply company.

[wchilton]

I bought the orange, minimum shrinkage stuff. Also, some dark blue that was even harder, but I never worked with the dark blue. Recommend getting flakes or pellets rather than in block form. The blocks came in a disposable "tin" that was stuck to the wax. You'd have to use a hand saw to cut up the blocks for melting smaller amounts, a knife won't do it very easily and electric saw melts the wax and then it sticks to the blade.

[mark poulson]

Thanks. I'll keep that in mind. Melting the pellets with a heat gun shouldn't be hard to do, to make the size block I need for carving.

[Richard Prager]

Have you thought about making your own compound? You can get a one pound block of pure paraffin which is very hard and stiff and mix in some beeswax which is softer and more pliable . Both should be available in the grocery stores for just a couple of bucks. As far as the jewelry wax goes, I was in the business and preferred to work with the green. You don't carve the jewelry wax. You heat up a dental tool and melt away to form your model. Just a thought

[atijigs]

Blue inlay/onlay wax will be solid at 99 degrees. At roughly 103-106 degrees it becomes soft. The best way is probably a water bath. In its solid state it can be carved very easily. The outcome is what matters. You can add wax in small increments by heating a small curved instrument and dipping it into solid wax. As with anything it takes practice. Paraffin with beeswax will work. Much cheaper and easier to get. As far as detail and finish goes there would be no comparison. The learning curve is very steep for carving/molding dental inlay/onlay type one hard wax. The results are very precise.

This would be my solution to your question. Make your model out of clay or whatever you choose. Don't worry about undercuts. Use alginate (can be purchased at craft stores)in the area you would find the sculpy clay. You will recognize it because they use it for taking impressions of babies hand and feet.----There are some undercuts there. Now you can pour melted wax of your choice in that mold. Paraffin would work. Just get it to the point it is liquid. Pour it in and you have your wax model. I have never tried this. This is theory only. As with any mold making your results depend on the model. Alginate needs to be mixed carefully to avoid air bubbles. Water to powder ratio needs to be exact. I am sure the mold will hold up for at least one pouring of warm liquid(low melting wax). That's the best info I can share given the result you are searching for.

I find it very difficult to explain in a few sentences what took me many years and mistakes to learn. I hope this is of some help and not making it more confusing. For instance-we use a special spatula and rubber bowl to mix the alginate. You probably are not going to have this stuff laying around. Good luck. It can be done.

[atijigs]

After reading my post I thought I should point out that you will be sacrificing your alginate impression to retrieve your poured wax pattern. The alginate will be soft and if you are careful you may be able to cut it with an exacto or other type of razor blade for another try. The alginate impression will only be good for an hour or 2 at the most. Once it dehydrates the flexibility is gone.

Edited March 23, 2012 by atijigs

[longhorn]

I have used parafin (common canning wax) to make lost wax POP molds with good success. I bought some of the blue carving wax and never could get it to melt so it didn't work for me.

[mark poulson]

Man, I never thought about parafin! I have a case of parafin blocks in my garage that a friend brought me. It fell off a delivery truck and was on the side of the road.

And I have some beeswax, too.

Thanks.

[ROWINGADUBAY]

I was going to ask the same question the other day I used to work as a quality inspector at a foundry that made there molds by molding wax in an aluminum mold dipping the wax in some type of ceramic then after the ceramic dried they would melt the wax off pour most of it out then put it in a kiln any wax left would burn off this would also pre-heat the mold to pour the steel . We made alot of rocker arms like this for nascar.

when I use sculpey I can never get it nice and smooth I think wax would be the way to go

[mark poulson]

I was going to ask the same question the other day I used to work as a quality inspector at a foundry that made there molds by molding wax in an aluminum mold dipping the wax in some type of ceramic then after the ceramic dried they would melt the wax off pour most of it out then put it in a kiln any wax left would burn off this would also pre-heat the mold to pour the steel . We made alot of rocker arms like this for nascar.

when I use sculpey I can never get it nice and smooth I think wax would be the way to go

Great minds think alike!!! Hahaha

[longhorn]

Here's a parafin swimbait I carved about 5 years ago.

[atijigs]

I went ahead and did a little experiment. I did find out that wax could be poured in the alginate impression. The only problem being shrinkage. As the wax cooled the hard moldel shrunk somewhere in the range of 15%. This was with the blue casting wax. It is really designed to be added incrementally to limit shrinkage. I did however repour the alginate with dental stone(higher quality than pop). I got a very nice stone reproduction of the bait. It was a used bait. The detail was so good the areas that a hook was removed showed up in the solid model. Now those details could be nicely fixed with casting wax to get a perfect model. The alginate can be a little tricky to work with but it works. This was my first attempt at using it for this purpose. I had my assistant take some pics during the process with her phone. If they are any good I will post them to show the technique.

[quietfly]

i look forward to seeing the results.

I've been making my replications in smooth on 325. i like it because its VERY workable after it sets and i use my rotary tool to make adjustments to the model.

[atijigs]

Here are the results from my experiment. First try using alginate to make wax master. It worked but had too much shrinkage to be viable. I did however like the results for making a stone master. I would do it a little different next time. Using the alginate is a relatively cheep alternative to silicone. Advantages are it sets in minutes and will not stick to itself once it is set. That means no separating medium required. Ideal for a quick easy 2 part mold.

Disadvantages- It sets really fast. Using cold water slows the setting a little. You have to work quick.

It doesn't last. You will want to use your mold right away. I kept this one viable for 3 days by keeping it wrapped in wet paper towels in a sealed baggy.

I was able to pour a couple actual baits directly from the mold. The heat of the plastic immediately starts the deterioration and drying out of the mold.

I would want a mold box next time. Alginate won't stick to it but it would help to have some support when pouring. I just used rubber bands but without support it could cause distortion

[mark poulson]

I googled alginate, and watched a U tube video of a guy making a mold of his hand and forearm.

Interesting stuff.