If you don't own a pressure pot, get one!

[MesquiteMan]

If you don't have a pressure pot in your arsenal, you really should think about getting one! I picked one up at a garage sale a number of weeks ago for $10 so they can be had inexpensively. I have been using them for my cactus blanks and have gotten rid of bubbles completely. There is another great use, however.

I had a number of oak burl blanks that had quite a few cracks and very small voids. In the past I have filled them wih CA with fair results. Last night I decided to experiment with the pressure pot.

I made a mold just barely bigger than the blank out of cardboard. I basically made an open top box. I then mixed up some epoxy and poured a thin layer on the bottom of the mold and dropped in the blank. I then covered the blank with epoxy to where it was basically submerged just a little. Then put it in the post and pressured to 55 psi and let it cure.

Once cured, I cut off the excess epoxy and cardboard with the bandsaw and turned a pen. ALL of the voids, even deep in the blank, were completely filled with hard epoxy! Much easier and better results than using CA while turning. This will also help keep it from blowing out when you have wood like that. Try it, you will like it!

 

[bonefish]

Do you use epoxy like in epoxy glue, or ther a type of casting epoxy available?

Bonefish

 

[cozee]

I guess I really don't understand the process. First, in terms of a pressure pot, are you refering to the one's painter's use? Are you using it instead of a vaccuum chamber, reducing the bubble size instead of removing it? You mention placing the blank into a post so to pressurize it and allow it to cure. What exactly is the post?

 

[Sir_Stinkalot]

I agree ..... would it be possible to go back to the bare bones and explain the process including details of the pressure pot and how to pressurise it.

Thanks

 

[cozee]

Never mind, I found the thread. Answered my questions as I thought. Using the pressure keeps the air molecules/miniscule bubbles from collecting and forming larger vissible bubbles. It doesn't rid the blank of air, it simply keeps it trapped and immobile. Kinda hard to imagine a pressure tank working any better than a vaccuum chamber when stabilizing. I'll have to give it a try.

 

[its_virgil]

Prepare the blanks (if imbedding something like snake skins),place in mold, add PR, place in pressure pot, connect to air compressor and pressurize the tank (I go to 45psi, but will be trying less), keep pressure constant, allow time for the resin to kick over and cure
(I leave mine in for 4-5 hours), release pressure, remove bubbleless casting, cut into blanks, turn for favorite pen, show us pictures of your creation.[]
Do a good turn daily and safe casting!
Don

Originally posted by Sir_Stinkalot
<br />I agree ..... would it be possible to go back to the bare bones and explain the process including details of the pressure pot and how to pressurise it.

Thanks

 

[MesquiteMan]

Cozee,

Uning vacuum with epoxy does not work very well unless you de-gas before pouring. Epoxy rises a bunch when under vacuum. The other thing is that when using vacuum, you are really supposed to pull the vacuum and then release before the resin cures and that is more of a problem than it is worth when using epoxy.

The advantage of pressure is that you can use use epoxy easily for the stabilizing. It fills larger voids and actually kicks in the wood. I have not tried it for punky wood, just for wood with cracks and voids and it works VERy well.

It is also something that the average person can get into with little cash. You can get pressure pots pretty cheap if you look aroung vs. a lot more for a vacuum pump.

For those that asked for clarification...the pressure post I am talking about is a paint pressure pot that used to be used by painters. DO NOT try to use a pressure cooker since they are not made for higher pressure!

 

[bonefish]

Could you describe the type of epoxy that you use, and where do you get it?

Is it different from Epoxy Glue?

Bonefish

 

[BRobbins629]

Just pulled my first pressure cast with epoxy (Mirror Coat System 3 - a little pricey but I happened to have some around). Don - you were right - its by far my best and clearest cast to date. I did mine at about 25 psi, left it in overnight and it was void free. Will not do another cast without one. Thanks for offering the tip.

 

[cozee]

Thanks MM! This seems like a twist in the injection molding process!!! Is the epoxy being used the typical 2 part? I have no problem locating pots as I am a bodyman by trade!!! 2 1/2 quart to five gallon, I've got a small selection of 'em at hand!

Side note: When using a vacuum chamber one doesn't need a $$$ vacuum pump if they have an air compressor. Air powered pumps with the ability to pull up to 29" run from $15-$30. Most only require 2-4 cfm at 90 psi thus one doesn't need a large compressor to operate them.

 

[elody21]

Curtis, How well does your epoxy polish up? I find I have problems with the sanding and polishing of the Devcon 2 part I use.

 

[its_virgil]

I'm glad you were successful and that you like the resutls. I too will never cast without using pressure again.
Do a good turn daily!
Don
'

Originally posted by BRobbins629
<br />Just pulled my first pressure cast with epoxy (Mirror Coat System 3 - a little pricey but I happened to have some around). Don - you were right - its by far my best and clearest cast to date. I did mine at about 25 psi, left it in overnight and it was void free. Will not do another cast without one. Thanks for offering the tip.

 

[JimGo]

Congratulations Bruce!

 

[alamocdc]

Originally posted by elody21
<br />Curtis, How well does your epoxy polish up? I find I have problems with the sanding and polishing of the Devcon 2 part I use.

Alice, I haven't tried the pressure pot thing yet, but I have long used epoxy to fill voids. I was told years ago by an old woodworker to use marine epoxy for this and have always been very satisfied with the result. It polishes quite nicely. The only drawback is cure time, but I've learned patience.[] BTW, I get mine at Lowe's.