Mini Low Pressure Pot to get rid of bubbles

Plokman

Active Member
Ok everyone, still trying to find a App that can ID wood but I wanted to ask another question, I need a pressure pot for my casting but I cannot afford a giant one yet and I also don't need a massive one yet. I am not crazy though afterall I know what happens to a pressurized vessel that can't handle it and has no safety valve I am a railwayman at heart and love Steam Locomotives, I do know one thing I can get the results I need with just 10 or 20 PSI as Ben's Workz showed a PVC rig that he tested with a 10 PSI load and got near clear (I say near clear due to the fact that the mold he used had a textured inside so it wasn't smooth but if sanded and polished it would be clear.)

I plan to build one with my pop since he knows pressure better than I do and once I find a hardware store with the right size PVC (Seriously Rual King where we normally got pipes was bear of them.) but till then I want a simple setup that I can rig and use, so does anyone know of another common household container that would hold 10 PSI and always closes Air tight?

Hmm recalling the Electrolysis Ruster I setup for Rust powder, as I feel using Rust as a pigment can give a nice Authentic embellishment to a prop if it's meant to be old, and it's inside plastic (Resin is as far as I am concerned a Plastic to the point where if you made a Resin Native American figure put it in a cupboard and turnd a key that it would work in the Indian in the Cupboard way. Also yes I know it's a oddity using "Indian" in the same breath as Native American but it is what the book is called after all and I mean no offense.) only thing I would worry about is if I used it as a pigment on a resin in a blank I planned to turn on a lathe.

Probably give that a sealing coat of brushed on Resin, but yeah I used a old Peanut butter jar for that and I had a blowout (If you know how Water reacts to electricity you know why, darn spark) but the only damage was the bottom bulged out but was easy enough to pop it back in so the jar sat flat again.

So yeah any ideas?
 

Kovnyn

Sr Member
How big of a pressure pot do you need, volume wise?
The company I work for does automotive component painting, so we have a lot of pressure pots, and when we phase out the older ones, we just throw them away. I do have a couple smaller pots, rated to 50 psi, and I can let one go. You may need to swap valves and regulators, but the lids and pots themselves are sound, just old, maybe slightly dented. I'll see if I can scrounge one to suit your needs.


EDIT: the pot I can get is about 314 cubic inches of volume. 2.5" Radius by 16" height.
 
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Plokman

Active Member
How big of a pressure pot do you need, volume wise?
The company I work for does automotive component painting, so we have a lot of pressure pots, and when we phase out the older ones, we just throw them away. I do have a couple smaller pots, rated to 50 psi, and I can let one go. You may need to swap valves and regulators, but the lids and pots themselves are sound, just old, maybe slightly dented. I'll see if I can scrounge one to suit your needs.


EDIT: the pot I can get is about 314 cubic inches of volume. 2.5" Radius by 16" height.
Oh wow that would be awesome, I'll need to talk to my father on when we can pay you shipping and any other costs. But yeah that sounds epic thank you very much and we can continue this conversation in PMs.

By the way be sure to grab any Fordite from the racks at your job that stuff is awesome and always in demand on Etsy and such since it has such unique patterns. I'm not asking you for that I am not a Maker of that skill level yet, just giving you a heads up.
 

Kovnyn

Sr Member
We clean our racks too often, and only use limited colors, to sufficiently build up any Fordite.

PM me your address and I will get a shipping estimate. If it's not too expensive, I'll foot the shipping. Maybe we can work a trade on it.
 

Plokman

Active Member
We clean our racks too often, and only use limited colors, to sufficiently build up any Fordite.

PM me your address and I will get a shipping estimate. If it's not too expensive, I'll foot the shipping. Maybe we can work a trade on it.
That would be great, I'm not sure what I can offer in trade but I will pay the shipping fee and maybe a tip (A good one too not a buck on the table kind of tip ;) ) I'll pm my address in a moment, I can't thank you enough.

Also such a pitty on Fordite chances. Too bad a home method couldn't be done cause as far as I know Fordite is getting as rare as a working Steam Locomotive. Can't wait to see UP No. 4014 in action a Bigboy class is the pinnacle of a American Railwayman's experience. Heh yeah I love trains especially Steam.

You know it may be worth trying to find a home Fordite production method, I'd certainly give it a go to keep a art form alive, much like Steam Locomotives.
 

Kovnyn

Sr Member
Home made Fordite actually wouldn't be all that hard. You'd just need automotive exterior paint, mixed with the correct hardener, a decent spray gun and compressed air. On a sheet of stainless steel, lay down layer upon layer, a few microns thick, switching colors every ten layers or so, allowing each previous layer time to cure. Once you have a nice sheet, oven bake it at about 150-200 Fahrenheit for about half an hour to an hour and a half. Cut and polish as you want.
 

Plokman

Active Member
Home made Fordite actually wouldn't be all that hard. You'd just need automotive exterior paint, mixed with the correct hardener, a decent spray gun and compressed air. On a sheet of stainless steel, lay down layer upon layer, a few microns thick, switching colors every ten layers or so, allowing each previous layer time to cure. Once you have a nice sheet, oven bake it at about 150-200 Fahrenheit for about half an hour to an hour and a half. Cut and polish as you want.
I may just try that when I move into my larger workshop, and built up enough skill to warrent the Spray system. After all I am just starting out as a Wood and resin guy my father knows more on Autos as he can fix any basic engine with the right parts. So long as it has no chip or complex modern computers, he just never could get the soldering of Micro Processors right, but anything Mechanical or with a Vacuum Tube in it I know he can fix, Again if we got the parts.

I feel like I just was talking about the movie Robots, the one from 2006 with Robin Williams and Ewan Mcgreggor and oh boy I know I butchered that name spelling for Ewan but that is what I get for using my Wii U to reply, Reloads every time I change tabs and that means all my text is lost to the digital aether.

Forgive my babbling, it's a problem well to some others find it a blessing but I take pain meds prescribed by my Doc for leg pain and it always seems to make my already long writing into thesis sized text walls. Anyway thanks for the idea as well as everything else my friend, I'll do my best not to cause another case of oversight on worry. I have a bad habit of worrying about those I consider friends and I'd rather not do it again to the point of crossing a line if you take my meaning, take care and hope you have a great weekend.
 

E Williams

Sr Member
RPF PREMIUM MEMBER
It looks like you're covered as far as pressure chambers go, but I wanted to mention that if you are only looking for low pressure you might investigate a vacuum chamber. The re-pressurization after drawing a vacuum is equivalent to putting the casting under about 14 psi pressure (in addition much of the entrapped air will have been drawn out during vacuum). They're also quite a bit safer than pressure pots.
 

Plokman

Active Member
It looks like you're covered as far as pressure chambers go, but I wanted to mention that if you are only looking for low pressure you might investigate a vacuum chamber. The re-pressurization after drawing a vacuum is equivalent to putting the casting under about 14 psi pressure (in addition much of the entrapped air will have been drawn out during vacuum). They're also quite a bit safer than pressure pots.
I will have to disagree on how useful a Vacuum Chamber is for Resin degasing, Since the surface tension of the uncured resin is often thicker than water it will bubble like a grade school milk carton. Peter Brown recently showed that if you try the Vacuum Method the bubbles won't break quickly and froth up and out of the container, so unless you sit with the pot and release the vacuum every time it gets to the top you'll end up with the same effect a shaken soda in a bottle has.

I agree they are much safer but are useless to a degree for most resins, the exception is Cactus Juice and that is for stabilization of porous and light objects. They are perfect for Silicone degasing but even that must be tended to a pressure pot und no more the 30 PSI is sufficient as Ben's Workz showed with a home built PVC chamber to remove the bubbles and if I read right the pot Kovnyn is working with me to get has a 50 PSI limit.

I fully understand the Pressure danger and I really do know what it can do, as a steam locomotive lover I know all too well what too high of a pressure can do. But unlike steam which is a constant expander so long as it has heat and takes up 1600 times the volume the water it came from, Air is not constantly shifting from large to larger.

Plus I have my father to help me as he's got a good 30 years of experience on me to ensure we take every precaution. I do intend to get a Vacuum Chamber as I do have some things that I wish to infuse but not at this moment is it cost effective.

I do hope I didn't come off sounding rude there, I appreciate the advice I really do but it's something I could reasonably do with resin especially once I upgrade to epoxy resin. Polyurethane based resins are far too sensitive to moisture and I live in Illinois so if I even breath near it incorrectly it's ending up looking like a Slushy or Italian Ice dessert but that is nither here nor there.

Thank you for the advice, I always getting feedback to help me improve after all this is what RPF is for helping, inspiring, and creating. Also thank you very much for just looking out for me with safety, I know how fragile life is and those who do their best to keep others even strangers safe I have a deep respect for as it was something my Mother used to do and my poppa as well.
 

E Williams

Sr Member
RPF PREMIUM MEMBER
Many prototyping shops exclusively use vacuum casting, though it's done with the help of expensive vacuum ovens which have mechanisms to mix and pour the resin under vacuum. You certainly won't get quite as good results at home, compared against both vacuum oven or pressure chamber methods, but it's a method that's worked well enough for me in the garage. I've had a lot of success with getting bubble free castings with clear parts, for example. The key is to allow for the volume of the foaming resin when designing your mold - typically via a large cavity above the pour spout/vent. Using a longer pot life resin that can be degassed both before and after pouring also helps.

You'd mentioned wanting low positive pressure on your curing resin - just throwing it out there because it's a method which will do just that.
 

Plokman

Active Member
Many prototyping shops exclusively use vacuum casting, though it's done with the help of expensive vacuum ovens which have mechanisms to mix and pour the resin under vacuum. You certainly won't get quite as good results at home, compared against both vacuum oven or pressure chamber methods, but it's a method that's worked well enough for me in the garage. I've had a lot of success with getting bubble free castings with clear parts, for example. The key is to allow for the volume of the foaming resin when designing your mold - typically via a large cavity above the pour spout/vent. Using a longer pot life resin that can be degassed both before and after pouring also helps.

You'd mentioned wanting low positive pressure on your curing resin - just throwing it out there because it's a method which will do just that.
Fair enough with the right experience it could work better in practice, sadly I do not have that much experience and not a whole lot of money. Over the last six months I've gathered the key tools but I still lack quite a few, till I am able to setup my shop and sell some of my crafts I need to invest in items I can use with my current setup. As of the moment I have a air pump and compressor but I do not have a Vacuum Pump, and as I mentioned above being a lover of railways I know Air and Vacuum pumps are very differnt beasts.

When I have the money to buy a good Harbor Freight Pump I'll definitely give your method a try, I will of course need coaching so I'll be sure to get in touch with you when I reach that point. After all I do want to get a Vacuum Pump for my mold making silicone eventually, it's a good thing I have been somehow got a really good Silicone that has great self degassing formula but Those molds won't last forever and I'll need better grade stuff at some point.

My friend like I said above I do appreciate the advice, I would never be ungrateful for any help in my prop making work. I really do hope I didn't sound angry because I wasn't and am not now either, I wish you nothing but the best and I look forward to anything you may have to share project wise. Thanks very much for the info on that method but for now the best setup for me is Air Pressure to remove bubbles.

By the way what kind of Resin do you use? I'm doing research for resins that don't act so violently to moisture, I know it sounds oxymoronic but trust me the stuff I have now is Polyurethane based and I know for a fact some resins will cure if not softly (Press your thumb to the cast and a indent is made that sort of thing it still is set) at worst when a small ammount of water gets in, Peter Brown has used hot sauce as a pigment and it came out slightly gummy but as a display piece or like a badge it would be fine for.

My Polyurethane stuff will go nuts if a residual bit of moisture is in the pigment or item being cast, That is very bad since I want to use real rust for pigment on some things and I may need to heat it a bit more to fully dry it but it's a fine powder it should mix in if I put less than a gram in if a squirt of mustard (Enough to put on a hot dog) does.

Hope that last bit made sense after all I've seen Orbeez put in to a resin and it set but it was a bit messy at the edges.
 

E Williams

Sr Member
RPF PREMIUM MEMBER
I haven't needed to cast any overly large items, so trial size resin kits have been enough. For opaque castings, I'll usually go and grab the cheap Alumilite trial kit from Hobby Lobby ($18 after coupon) that has 2 pints of resin; they used to carry a slower setting Alumilite that worked much better with my low-rent set-up but alas, no more :). I've used some Smooth-on (300, 325) with fair results but it's not overly humid in my workspace so I can't if any of the above would be easier for you. I'm sure there are better products out there but I'm usually just casting rather small parts and hand prop components, or filling shelled 3D prints for weight/strength, and this stuff is easy to get/close at hand.

For clear items I really like Alumilite's "Water Clear" which can be ordered from Alumilite directly, or occasionally for a good price on Amazon - it is worlds better than the Alumilite "Amazing" Clear Cast found at Hobby Lobby, the actual properties of which belie the name.
 
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