# Pressure Pot



## MLWilson (Jun 28, 2015)

So, I've got all this cracked up wood lying around, mocking me, and I'm thinking about going all resin filling on some of it. (I currently have, on the lathe, rough turned, a Maple bowl that calls out for something special, for instance.) I need resin that won't break the bank, and, I need a pressure pot. This missive concerns, mainly, the pot. Here's the deal: I'm looking at the $100 "Paint Pressure Pot" that HF offers, and I read the reviews on it. I see that lots of people have used this 2-1/2 gallon pot for just the thing I want it for. But what I also read is that these people have, as they say, "converted" it for such use. I have no idea what that means. What must one do to "convert" a paint pressure pot for use with casting/epoxy resin? I know many of you are in the loop on this topic. Some detailed instruction would be greatly appreciated.


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## John Smith_inFL (Dec 15, 2017)

Mark ~ are you talking about making a vacuum pot for impregnating wood
with resin (cactus juice) under a vacuum vs pressure ??
then - bake it in the oven for several hours ?
if that is the case, then there are special resins involved that are totally
different than the common casting resins and structural epoxies.
also, you need a vacuum pump and not a compressor.

.

.


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## BFamous (Jan 26, 2018)

I've done lots of resin casting in a pressure pot (used to make car bodies for those old HO slot cars we all had as kids…).
Smooth-on was my go to resource for resin. Though not certain if there is wood specific resin to use.

As for converting the pot, the only thing I had to do was remove (aka unscrew) a metal piece on the inside of the lid that went down into the open space that blocked me using it. I also made a flat bottom, as mine pot had a rounded base which meant I couldn't rest things flat.


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## Nubsnstubs (Aug 30, 2013)

Mark, if you do get this tank, the siphon tube should where the 90 degree fitting is. Remove the tube. Remove the tee. Separate it from the regulator. The regulator has one inlet and 3 outlets. Install the regulator directly onto the tank, noting air flow direction if indicated. Put the gauge where it wont get damaged near the handle. Install a ball valve into the inlet with a quick coupling. This is done so you can unplug your tank from the air supply when you reach pressure, enabling you to still use the air supply for other things while waiting for the resin to cure. You will need to plug one hole on the regulator. 
Put another ball valve on the 90 degree where the siphon tube was. I do this so I don't contaminate the regulator when I release the pressure. It's a habit I picked up when I was using my tanks for spray painting… If you need to see a picture, I'll send it to you…..... Jerry (in Tucson)


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## LeeMills (Nov 2, 2014)

I am not sure if HF has different models but here is one who shows converting to a standard air line hookup. I have an HVLP turbine and the fitting for it are different sizes than a standard air compressor would use.


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## Wildwood (Jul 22, 2012)

Never done it but have looked into it from info posted in IAP library;

Pressure & Vacuum pot 1
http://content.penturners.org/library/tools_and_jigs/pressurepot.pdf

Pressure pot for resin casting 2
http://content.penturners.org/library/casting/pressure_pot.pdf

Pressure pot 3
http://content.penturners.org/library/casting/pressure_pot_tech.pdf

Setup HF pressure pot 4
http://content.penturners.org/library/casting/setup_hfpp.pdf

Similar 41 Clear polyester casting resin
https://www.carbonfiberglass.com/Resin-Systems/clear-casting-resin/Silmar-41-Clear-Polyester-Casting-Resin-Gallon.html

Polyester resins
http://www.douglasandsturgess.com/mm5/merchant.mvc?Screen=CTGY&Store_Code=DAS&Category_Code=POLYESTERRESINS

Hope some of this info helps.


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## Nubsnstubs (Aug 30, 2013)

> I am not sure if HF has different models but here is one who shows converting to a standard air line hookup. I have an HVLP turbine and the fitting for it are different sizes than a standard air compressor would use.
> 
> 
> 
> ...


Mark, this video explains the conversion very well, except for the second ball valve. ......... Jerry (in Tucson)


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## RichBolduc (Jan 30, 2018)

I've done the HF Conversion for casting resins. Overall i'm maybe $100 in to it. This is what the top of mine looks like after the conversion. I usually run it about 50-60 PSI










Rich


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## Nubsnstubs (Aug 30, 2013)

> I ve done the HF Conversion for casting resins. Overall i m maybe $100 in to it. This is what the top of mine looks like after the conversion. I usually run it about 50-60 PSI
> 
> 
> 
> ...


Yep, that's what I did to mine. Two ball valves to keep the regulator clean.

Rich, have you ever lost the 2 screws on the back of the regulator. It seems every regulator I own, probably 6-8 of them, the screws fall out if not caught before they do….... ............. Jerry (in Tucson)


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## Andybb (Sep 30, 2016)

+1 on the above conversion on the HF pot. Plenty of youtube vids on it. I had to remove all of the fittings to keep it from leaking but you need to re-do most of them anyway to do the conversion. The pipe goo they use dries hard and doesn't always seal well. Also, note that the relief valve is adjustable if it hisses at 50psi. I have mine set to about 55psi and pump it to 50.

Alumilite seems to be the standard resin for a pressure pot but there are resins you can use that don't require a pressure pot. Resin Casting Without a Pressure Pot

If the wood is punky and you're going to stabilize the wood first you will need a vacuum chamber too.


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## lew (Feb 13, 2008)

+1 on the alumilite.

If you warm it in the microwave, prior to mixing the 2 parts, the bubbles will migrate out easier. You may be surprised with the results and may not need the pressure pot.

BTW, looks like LJ buddy post notifications not working again.


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## Nubsnstubs (Aug 30, 2013)

> +1 on the alumilite.
> 
> If you *warm it in the microwave,** prior to mixing the 2 parts*, the bubbles will migrate out easier. You may be surprised with the results and may not need the pressure pot.
> 
> ...


Mark, I wouldn't recommend heating it. Last year I misread the instructions on the Alumilite that I had. I set it in the sun to warm up, and it took at least 5-6 minutes off the 12 minute pot life. I mixed up 16 ounces each, added color and powder to the A side first, then mixed the 2 parts together in a coffee can. It was stirred for 3 minutes, then when I started pouring it, it started hardening before I was done with the pour. The can I mixed the two parts in got so hot it was almost unbearable to handle. I contacted Evelyn at Alumilite and was told all it needs is 125 degrees to cause the thermal reaction to start setting. Apparently the temperature was too high when I started, and I knew the quantity was going to help cause the thermal reaction sooner, but not that quick.

You can do it the way you think will work best for you, but keep it at ambient temperature until it's poured. Then yopu can add heat if you think it's necessary….. Jerry (in Tucson)


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## MLWilson (Jun 28, 2015)

Okay, guys. Thanks for all the very erudite answers.

Let me be clear: I was born without the mechanical engineering gene. I pulled up, and watched and or read, some of the above links, and carefully examined the photos you included, about "conversion," and whatnot. My head is spinning. "Beyond photos and videos, I've never even looked at an actual pressure, or vacuum pot.

Here's the video that got me hot on this topic. (skip to about 4:30)






This is the kind of activity I'm looking forward to engaging in - taking a piece of wood that's decidedly un-whole, and filling large voids to make something spectacular like Brother Andy does. Brother Andy doesn't speak in his videos, nor is he forthcoming about his methods.

Now, when I look at Andy's pot, I see no evidence of any complicated doohickery. The thing I really want to see, and know, is whether the pot is being pressurized or evacuated. Once I get my head wrapped around that not-insignificant matter, I suppose I can concentrate on the doohickery of making a pressure pot suck, instead of blow. I know that the objective, in any case, is to make the resin cure without bubbles. Whatever effects any addition of colorizing additives or mica and such has on that is another question, altogether, perhaps befitting a more molecular scientist aptitude than I possess. At this point, I feel as though I've whacked a hornets nest.

I know. I asked for "detailed instruction," but. right now, seriously, Beloved Buddies, baby steps are called for. Maybe I'm overthinking it all. No. I *am *overthinking it all. Count on it.

I'm rubbing elbows, here, with some absolute geniuses. I will be, shortly, PMing at least two of you, and begging you to put yourownbadselves in the shoes of a pre-school teacher, and really dumb this thing down for me. You know who you are.


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## Nubsnstubs (Aug 30, 2013)

Mark, I have 2 pressure pots. One is a 2 1/2 gallon Speedair pressure pot from Graingers, bought in 1980 when I was in business for spraying colored lacquer only. I removed stuff for painting, and left only the air inlet and relief valve. The air is regulated before going into the tank. After the tanks is filled, I check for air leaks and close off the inlet valve if I find no leaks. The air hose is then uncoupled from the tank.It I chose to let it sit a month or year I could do so as long as the tank doesn't leak down. When I'm ready to open the tank, I release air through the second valve, then open it to remove the parts that were cast.

The other tank is one I made last year. It's made from 1/4×6 x 16" steel. It was made to either lay flat, or stand up, depending on what type of molds I'm using. The longest piece I can put in the tank is 14". The reason this is posted is to show the air supply points. I didn't put a pop off on this tank because it will handle well over 100 - 150 + pounds. I did put a gauge and I want to see the pressure reading. I also only have one valve as I decided I didn't need 2 valves.










This picture below is intended to show a bubble that has exposed itself. There are at least 20 bubbles that have become visible in the last 2 years. The other bubbles are shy, and didn't show in the picture, but they are there. I'm taking a wild guess and say they are there because of excessive pressure, 80 pounds, when this piece was cast. Now, the piece has been sitting with my dog in it for several years, the bubbles are wanting to escape. It is Alumilite, and the recommended pressure is 40 pounds…...










I have another piece of just Alumilite I vacuumed. I made up too much mix, vacuumed it, made the pour and pressurized it. What was left was left in the cup to harden. Next day, the stuff was as hard as a rock and full of huge bubbles.










Another one I have was done as an experiment to see if I had passed shelf life on the Alumilite I had. Alumilite has a 90 shelf life on their "Clear" stuff. I had it over 4 months, so decided to test it by mixing A&B together, stir it and let it sit until the next day. It was as hard as the red piece but looked like it was frosted. I turned each to see if it was workable. Here is the frosted piece. This is the clear resin that is supposed to be water clear. Millions of tiny bubbles. The black spots you see is possibly embedded sanding grit. The stuff was clean when I mixed it.










Both pieces are under 2 1/4" . Here they are together.










............ Jerry (in Tucson)


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## LeeRoyMan (Feb 23, 2019)

I've always wanted to do this myself, but like Mark I don't get it. I understand a pressure pot, but don't you want to apply vacuum to the pot to pull all the air out of the resins and into the wood?


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## MLWilson (Jun 28, 2015)

Jerry, your "homemade" device is exactly what I'm talking about, when I say, "You're a genius." I don't have what it takes to just make what I need. That's what farmers do. A farmer, I'm not.

So, Jerry, the one with the big bubbles was done with a vacuum? I don't get it. Vacuum means there's no are in there to make bubbles. The "frosted" piece is easy to understand, if you let it sit, unpressurized or un-evacuated.
So, what's called for is, definitely, vacuum. This is what I'm picking up. Now, are there pots available for that? Or, does one really need to "convert" a pressure pot? Again, with regard to that, Brother Andy's pot doesn't look modified.


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## John Smith_inFL (Dec 15, 2017)

my head is still stuck in the physics of it all.
I am building a *vacuum* system to where the air is removed
from the tank thus there are no bubbles in the resin when it's done.
and the air is sucked out of the wood also, letting the resin seep into
the pores and fibers of the wood.

I guess my question is this: has anyone experienced the reverse effect
of the pressurized resin popping loose once it acclimates back to the ambient
pressure ??? sort of like with divers that come up too fast from the ocean depths 
and the air expands in their body causing all kinds of problems.

I'm with Mark ~ trying to pay attention from the back of the room and learn something new.

.

.


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## Nubsnstubs (Aug 30, 2013)

> I ve always wanted to do this myself, but like Mark I don t get it. I understand a pressure pot, but don t you want to apply vacuum to the pot to pull all the air out of the resins and into the wood?
> 
> - LeeRoyMan


When the resin is under pressure, it will travel where ever it can. What the air pressure is doing is compressing the air in the wood, or what ever you are casting. The resin is a solid liquid?? and will not compress. It will travel into cracks, holes and whatever it can get into because it does not compress like the air does. When the compressed air does escape, the bubbles will be tiny, but when they breach the resin, they will create a 1/4" depression.

I know this because just 2 days ago I was given 2 pen blanks that are clear resin. There is a defined bubble leaving the bark, and at the top of the resin is a depression caused by the compressed bubble bursting through the resin. I hope you can see this in the 2 pictures below. In this picture, if you look closely at just about dead center, there is a white dot on the left edge of a black area. On that left side of that white dot is a bubble that tried to make an escape, but got frozen in place by the setting resin. There looks to be another bubble at the top of the blank, but it has nothing to do with what I'm showing. It's a light reflection for a bubble on a corner of the blank.










This picture shows the depression of a bubble that did make the escape. It's about a 1/4" OD and about the same depth….. 









I learned a term when I was in the Army. I was a heavy equipment operator, so naturally I was sent to mechanics school to learn to work on engines. One thing that was brought up was a Hydro-static lock. I hope that's the term. How it was explained was how pistons and a compression chamber works. You have an air fuel mixture in a cylinder when the piston is down and the valves are closed. When it comes up it is compressing the air fuel mix. It reaches the ignition point and all is good. But, when the piston was at the bottom and if it had drawn in too much fuel, when the piston started compressing the air fuel mix, if there was too much fuel in the cylinder, more that likely the engine come come to an instant stop, or if running at rpm, would blow a hole in the top of the piston.

So, lesson learned is, you can compress air and gasses, but you can't compress liquids or solids….... ........ Jerry (in Tucson)


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## mrg (Mar 10, 2010)

> my head is still stuck in the physics of it all.
> I am building a *vacuum* system to where the air is removed
> from the tank thus there are no bubbles in the resin when it s done.
> and the air is sucked out of the wood also, letting the resin seep into
> ...


Vacuum is used to stabilize wood with Cactus Juice to remove all moisture from the wood. Pressure is used to compress resin like Alumilite so that it has no bubbles. If the wood has any moisture when you go to cast you will end up with white spots and in some cases failure between the wood and resin.

Filling voids and such under pressure the resin will work its way into the voids. When hardened it will stay put.

Check out Zac Higgins channel on YouTube. A random video about casting without pressure.


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## MLWilson (Jun 28, 2015)

John: Hang around. Some of these cats are geniuses. Some of it might rub off.

Speaking of rubbing off:

mrg: That's helpful. Thanks.

Jerry: What mrg said struck a nerve - wrinkled my brain. Moisture in the receiving material is a thing to reckon with, I'm sure. Is that "vapor lock?"


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## Nubsnstubs (Aug 30, 2013)

I'll show you a casting I did that I thought was dry. Man, is it messed up? The two ends cast fine, but the middle has a million bubbles. I cast two other pieces of the same stuff, and they cast fine. maybe my dog did something when i had my back turned….. Later today, tune back in….... Jerry (in Tucson)


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## Jim Jakosh (Nov 24, 2009)

Mark, this is a timely post as I am in the process of buying or making a pot to hold both pressure and vacuum. As I understand it, The pressure is used to minimize/shrink the bubble size in a process like a clear resin pouring like I have been doing ( I used a propane torch to eliminate the bubbles when the come to the top).
The vacuum is used to evacuate all the air out of the fibers of a piece of wood so that the resin can penetrate and stabilize it when it hardens.

I have looked at the HF pressure pot for $100 ($75 on sale) and also the vacuum pumps ( $79 for a 2.5 CFM and $159 for a 3.5 CFM. Can someone tell me if the 2.5 CFM pump will be adequate for evacuating wood for stabilizing it??

Very good topic…........Thanks, Mark

Cheers, Jim


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## MLWilson (Jun 28, 2015)

Jim, I'm glad you weighed in. As it turns out, on the piece that got me hot for a resin fill, I've decided to just fill the voids with 15min epoxy. Here's a funny thing I've noticed: I filled the most major space with the epoxy this morning and the rest when I got home tonight (minutes ago, in point of fact) and, this stuff doesn't seem to be foggy. I mean, I simply loaded it in there, sitting in such a way that it would drool in, not even concerning myownbadself with bubbles. And now, about twelve hours later, it looks clear to me. I've used the stuff in the past, for filling cracks, and never noticed any fogginess. I haven't turned into it yet, though. I may have a different report to make about it tomorrow. Isn't "epoxy resin" of the pouring sort the same as that which comes in a syringe, but of a different viscosity and open time?


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