Chip Sawdust

Making and turning resin castings

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I searched here and there for information on this but thought I'd ask this sage group of wood turners about it. I was browsing the latest Woodcraft catalogue, and I've pondered this before... I saw a burl with resin, turned into a nice vase. I thought wow, that's awesome, and my wife loved it too.

So I'm thinking of doing something like this in the reasonably near future. Does anyone here have experience with this nook of turning? I'm looking for different ways to make molds, hints on using the resin, tools to use in turning (I assume they're the usual suspects but...) and that kind of info. There's a bit on YT about it but hey, I don't know those guys! :) 

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Not me, but I think @Gary Beasley said he'd done some.  Also look up Keith Lackner on  You Tube, he's well known.  I can't remember if you use carbide tools, but I understand that resin turns better with these.  Also, gotta tell you, resin ain't cheap.

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Chip, a friend of mine turns a lot of pens and duck calls. He uses Alumalite heat-cured resin and a vacuum pot to infuse the wood. IIRC, he doesn't require a mold, as he isn't filling large voids. He told me that he pulls the piece out of the vacuum pot and wraps it in foil, then bakes it at 200 degF for a while, maybe 20 minute (?). Then it is cured and turns as described above. If you want more details, I can ask him tomorrow.

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That's actually a process for stabilizing wood, especially punky stuff.  The vacuum is used to infuse the wood with resin.  The pressure pot is used to compress the air within the resin itself so that air pockets don't develop.  Stabilizing is another black hole.

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16 hours ago, Just Bob said:

That's actually a process for stabilizing wood, especially punky stuff.  The vacuum is used to infuse the wood with resin.  The pressure pot is used to compress the air within the resin itself so that air pockets don't develop.  Stabilizing is another black hole.

Is it recommended to use the vacuum to start, to infuse the resin in the wood, then finish up by pouring resin in the mold? Or is that necessary? I’d think with more porous wood that would be the thing, but with a good hardwood, like a walnut burl, maybe not?

 

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18 hours ago, wtnhighlander said:

Chip, a friend of mine turns a lot of pens and duck calls. He uses Alumalite heat-cured resin and a vacuum pot to infuse the wood. IIRC, he doesn't require a mold, as he isn't filling large voids. He told me that he pulls the piece out of the vacuum pot and wraps it in foil, then bakes it at 200 degF for a while, maybe 20 minute (?). Then it is cured and turns as described above. If you want more details, I can ask him tomorrow.

Yes I’d like to hear more about that. I’m thinking probably not pens, but bowls, vases, things like that. I’m planning on using Alumilite but might try some different epoxies depending in the project. I understand epoxies aren’t asile made shiny unless you put a clear coat over the top. 

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@Just Bob that’s a great story Bob :) and thanks for the info. I see HF has a 2.5 gallon pressure pot for $99, and there are some fittings to buy to convert it for use. There’s a guy on YT had a video about that. I think what binds my brain is all the rest of it, pouring resins in molds, experimenting and throwing away bad stuff... I’m not the most artistic person in the world but sometimes I make something really nice by accident!

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26 minutes ago, Chip Sawdust said:

Is it recommended to use the vacuum to start, to infuse the resin in the wood, then finish up by pouring resin in the mold? Or is that necessary? I’d think with more porous wood that would be the thing, but with a good hardwood, like a walnut burl, maybe not?

 

No, stabilizing is only necessary when the wood is punky, google "cactus juice" there is a ton of information related to this product and its use.

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Chip, the stabilized wood polishes to a nice shine, although my friend generally finishes the pieces with a coat of CA for added durability. I do know his vacuum pot is about the size of a 1-gallon ice cream bucket, suitable for small parts only. I'm pretty sure the infusing process scales up, though.

He tells me that it helps even solid wood to be more durable, but tight-pored species are tough to infuse. Harder vacuum and longer times.  For high-use items, like pens, bird calls, tool knobs & knife handles, he highly recommens it. Casting, even under pressure, leaves the wood parts wood. The epoxy is thicker, penetrating nooks and crannies, but not so much the wood pores.

So, vacuum infusion for parts that look like wood but are tough like resin, or pressurized casting for filling voids without bubbles and creating colorful areas.

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Bob I understand that pressure reduces the size of the air bubbles in the resin while it cures. I have yet to figure out why a vacuum isn't pulled on the resin first to remove as much air as possible and then pressure applied to shrink the size of the remaining bubbles. Could you shed light on why both processes aren't used?

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51 minutes ago, Chestnut said:

Bob I understand that pressure reduces the size of the air bubbles in the resin while it cures. I have yet to figure out why a vacuum isn't pulled on the resin first to remove as much air as possible and then pressure applied to shrink the size of the remaining bubbles. Could you shed light on why both processes aren't used?

I'm not an expert, but when stabilizing wood using cactus juice or similar you are pulling the CJ and air through the pores to impregnate the wood into a solid mass.  If you look at the process, the vacuum creates a lot of bubbles, it then needs to be baked to stabilize.  Using a pressure pot to cast something in resin reduces the air bubbles as you know, it does fill pores, but doesn't fully impregnate the wood.  With all that said there really is no need to do both.  If the wood is punky or really unstable then stabilizing will make a more solid piece to cast.  

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25 minutes ago, Woodenskye said:

 With all that said there really is no need to do both.  If the wood is punky or really unstable then stabilizing will make a more solid piece to cast.

I was speaking of an epoxy type resin so a casting not stabilizing resin....

Frank Howarth did a casting recently where he cast sawdust to make a sphere. There have been a few other youtubers that I've watched do something similar but I can't remember who where, and they used just pressure. After processing the casting there were small air bubles that never made their way out of the resin causing imperfections. It seems to me like there is a lot to gain but trying to pull as much air out of the casting before one applies pressure to reduce the size of the remaining air. With the long cure epoxies that cure in days not minutes, time doesn't seem like the problem.

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Drew, what you describe sounds like sucking the air out, only to push it back in. Unless you use a long-cure epoxy and hold the vacuum for days, the bubbles trapped in the wood pores or tiny crevices isn't likely to be drawn out. Compressing the epoxy with seems to mostly just help it to form well around the outside of the wood.

Not to disagree with @Woodenskye, but if you are making an object that is subject to high levels of moisture during use, like a duck call, then stabilization is warrented, even if the wood is sound. Casting might be used after stabilization, if there are voids to fill. Think of a very coarse burl, or those turned pieces where the splintered end of a break is embedded in resin and turned. I've seen calls made both was, and both resin processes were used.

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Duck calls would be fun, and I'm a shotgunner but not much of a hunter. I tend to go with guy who have dogs :)

I really like the idea of a vase, a container for the kitchen, bowls, things like that. Is Alumilite food safe without treatment?

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17 minutes ago, Chip Sawdust said:

Duck calls would be fun, and I'm a shotgunner but not much of a hunter. I tend to go with guy who have dogs :)

I really like the idea of a vase, a container for the kitchen, bowls, things like that. Is Alumilite food safe without treatment?

I know making duck calls are a common use for resin castings, I have never seen anything to indicate that the cured resin is not food safe, but I would contact the manufacturer to be sure.  Personally I would be more concerned about the finishes used.  I use a petroleum based polish, that I wouldn't put in my mouth....

I started stabilizing wood many years ago, but just for my knife scales and gun grips.  The only reason I stabilized those was to protect them from the environment they would be exposed to.  I am not set up to stabilize now (it is on my list).  Voids occur with pressure pots, not because of the air within the wood, but air trapped in the mold when the resin is poured.  Part of the problem is with the quick setting resin I use, I just don't have time to make sure all of the large bubbles have escaped.  That is the primary reason I am switching to a slower setting resin.  

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I sort of doubt that alumalite, or any other resin we use, once cured, is any more toxic than your typical plastic spork.

Interpret that opinion however you like...

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13 hours ago, wtnhighlander said:

Drew, what you describe sounds like sucking the air out, only to push it back in.

I guess i was thinking it'd remove the trapped air that is introduced to the epoxy when it's mixed. Putting the pressure back on it may cause some dissolved air to go back in but with out mixing I don't anticipate that it would re-introduce trapped air. I'm not talking about air in the wood as much as I'm talking about air in the resin it's self. I believe Cremona vacuums all of his casting resin before he pours it into the casting mold. His practice tends to yield good clear results. I've seen others do resin castings that only used pressure and they came out cloudy. I'm only talking about the resin not the wood.

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The resin casting turning cloudy may have been the result of moisture if alumilite was used. Its very picky about moisture in the air and in the wood, for that reason alone stabilizing wood before casting gives greater success as it leaves the wood very dry if done right. Otherwise you will want to do everything you can to completely dry the wood before it goes into the resin.

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3 hours ago, Gary Beasley said:

The resin casting turning cloudy may have been the result of moisture if alumilite was used. Its very picky about moisture in the air and in the wood, for that reason alone stabilizing wood before casting gives greater success as it leaves the wood very dry if done right. Otherwise you will want to do everything you can to completely dry the wood before it goes into the resin.

I'm talking epoxy resin or a 2 part resin that is mixed. Not a 1 part resin that is heat cured.

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Alumilite, total boat, west systems, liquid diamonds are all 2 part resins.  Alumilite clear and liquid diamonds are going to be the clearest resin if mixed properly.  If you are using a very slow set epoxy, then using a vacuum could help remove the air and may create a less cloudy appearance, but it is still a better practice to use a pressure pot.  Most of the casting resins mentioned above have a quicker working time and pulling a vacuum to remove all the air would take more time than you have to work with.  Either method will still require some level of polishing to obtain the best level of clarity.  

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No matter what resin you use its still a good idea to keep the moisture content as low as practical just to avoid any unexpected reactions. Some resin systems will tolerate moisture better than others, do your homework on the ones you choose to use.

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48 minutes ago, Woodenskye said:

Alumilite, total boat, west systems, liquid diamonds are all 2 part resins.  Alumilite clear and liquid diamonds are going to be the clearest resin if mixed properly.  If you are using a very slow set epoxy, then using a vacuum could help remove the air and may create a less cloudy appearance, but it is still a better practice to use a pressure pot.  Most of the casting resins mentioned above have a quicker working time and pulling a vacuum to remove all the air would take more time than you have to work with.  Either method will still require some level of polishing to obtain the best level of clarity.  

Still doesn't really answer why people don't use both. If you can pull a vacuum to remove the large trapped air and pressure to minimize and diminish the small trapped air it seems like the best situation.

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34 minutes ago, Chestnut said:

Still doesn't really answer why people don't use both. If you can pull a vacuum to remove the large trapped air and pressure to minimize and diminish the small trapped air it seems like the best situation.

I will leave it to you to research, experiment or do whatever you need to get the answer you want.  

Why pull all the air out just to put air back in when working with somewhat tight timeframes.  Most people just use pressure, it works, why complicate.  KISS method works for me. 

Edited by Woodenskye

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