Vacuum Stabilization when do you stop?

[Cowboy]

So last night I took my pepper jar, 3 dry redwood pen blanks, a 50/50 mix of minwax fast dry poly/mineral spirits and a 20 oz soda bottle and put it all together. I cut and drilled the blanks and pulled 24" of vacuum on the whole thing. The blanks started to foam immediately which should be a good sign. I woke up this morning to expect to see the blanks sitting at the bottom of the poly, but they were not. 4 out of the 6 blanks are completely submerged, but 2 are still floating. The jar kept vacuum all night, so I think that is ok. Should I leave them under vacuum until they all sink?

Chris

 

[Dario]

try releasing the vacuum them pull it again. Do this a few times until all of them sink.

 

[alamocdc]

Chris, Dario is on the money.

 

[Cowboy]

I have released the vacuum and pulled it probably a half a dozen times already since I was making sure the vacuum was holding (vacuum gauge for this project is in the mail). So you are saying that cycling the vacuum will actually cause the wood to sink not time?

Chris

 

[pssherman]

Chris,
You could try applying a small amount of pressure, no more than 10 to 15 psi. The pressure will drive the poly into the wood by collapsing any air bubbles that are still trapped in the wood.
Since the jar can handle 24" vacuum this amount of pressure should be OK. A good safety measure would be to wrap the jar with duct tape to contain broken glass in the event that it should break. Also, it might be a good idea to place the whole assembly in some kind of pan or container to catch the poly if the jar broke.

Paul in AR

 

[loglugger]

Chris, I have made a screen out of plastic that came out of a Greek pepperoncini pepper jar and weigh the blanks down with 2 pieces of small metal. Pull a vacuum a half dozen times over 2 to 3 days. I also stand the blanks on end, just don’t pack them tight as they will swell a little and get stuck in the jar. Be real careful if you use air pressure. Have a good regulator so you know how much pressure you are using. With vacuum the glass will mostly fold in on itself, with pressure there will not be a save place in the shop if it goes.
Bob

I keep a vacuum until ther is not anymore bubbles.

 

[wood-of-1kind]

Would an empty 1 gallon paint can serve as a good pressure pot? This is what I have in mind to use as I build my unit. Comments would be appreciated.

-Peter-

 

[pssherman]

Originally posted by wood-of-1kind
<br />Would an empty 1 gallon paint can serve as a good pressure pot? This is what I have in mind to use as I build my unit. Comments would be appreciated.

-Peter-

Peter,
Probably not. Assuming that the lid is 6" in diameter there would be over 400 pounds pushing up on the lid with only 15 psi of pressure. This may be hard to hold down and maintain an effective seal. Also, I am not sure how pressure the seams can take before bursting. Then there is the issue of the bottom bulging outward and sitting on a rounded surface.

There was some discussion a while back about using the HF paint pot to produce pressure for casting PR.

Paul in AR

 

[Dario]

Chris,

Releasing the vacuum should allow the trapped air pockets to collapse...while doing so, the solution should get sucked in replacing/filling the air pocket. Same concept as putting pressure, though not as good.

 

[wood-of-1kind]

Originally posted by pssherman
<br />

Originally posted by wood-of-1kind
<br />Would an empty 1 gallon paint can serve as a good pressure pot? This is what I have in mind to use as I build my unit. Comments would be appreciated.

-Peter-

Peter,
Probably not. Assuming that the lid is 6" in diameter there would be over 400 pounds pushing up on the lid with only 15 psi of pressure. This may be hard to hold down and maintain an effective seal. Also, I am not sure how pressure the seams can take before bursting. Then there is the issue of the bottom bulging outward and sitting on a rounded surface.

There was some discussion a while back about using the HF paint pot to produce pressure for casting PR.

Paul in AR

Paul,
thanks for taking the time to respond to my question. You offer many valid points that I did not consider in terms how much upward pressure is exerted on the lid. Guess that I will have to raid mama's large pickle jar and try it out.

Regards,
-Peter-

 

[dubdrvrkev]

I've had some blanks that never sank. They turned just fine.

 

[redfishsc]

Originally posted by wood-of-1kind
<br />Would an empty 1 gallon paint can serve as a good pressure pot? This is what I have in mind to use as I build my unit. Comments would be appreciated.

-Peter-

If it is a nice, clean can, you can use it to *pull a vacuum* but not to use as a high pressure container.

Then again if you were to sandwich the thing between two slabs of 2X6, viced together with really long lag bolts, tighted up really tight, that lid won't go anywhere with pressure.


Uh, why don't *you* try that and then tell us how it worked[)].

 

[wood-of-1kind]

Originally posted by redfishsc
<br />

Originally posted by wood-of-1kind
<br />Would an empty 1 gallon paint can serve as a good pressure pot? This is what I have in mind to use as I build my unit. Comments would be appreciated.

-Peter-

If it is a nice, clean can, you can use it to *pull a vacuum* but not to use as a high pressure container. Uh, why don't *you* try that and then tell us how it worked[)].

Well, I tried it (paint gallon) as my chamber pot. In a word it didn't work[V]. The tin gallon just isn't strong enough for my little vacuum pump. It collapsed the walls within seconds of me drawing some air out with my small compressor. The good thing is that my fittings and vacuum pump(borrowed from an vacuum lifter) is really compact and powerful. Now I just have to locate a strong vessel that will withstand the vacuum pressure. I'll try the large pickle jar next and go from there. Here's some pics that clearly show my story.[]
-Peter-

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[terrymiller]

Peter you may want to try a 8" pipe for the chamber with plexiglass lid and bottom. It is big enough for the 1 gallon jar or paint can to fit into.

 

[wood-of-1kind]

Will a glass jar (pickle??) be capable of drawing 20" of vacuum? I'm really new at this thing and since I collapsed the paint can in seconds, I don't want to have shattered glass scattered. Is the jar a safe 'thing' to proceed with? Is 20" vacuum too much? If not, what should it be? Any tips would be appreciated since I try to avoid accidents (esp. when they involve me[)]) at all costs. What say the experienced experts here at IAP[?]

-Peter-[B)][8][B)][8] and possibly[xx(]

 

[Cowboy]

I am using a large "pepper" jar that I got from the cafeteria at work. I have been pulling 24" of vacuum on it with no problems several times the past few days. Actually it is sitting empty right now with a vac on it so the poly does not dry out. As others have suggested, put it in a 5 gallon plastic can incase it implodes. Another poster here stated that during the canning process high levels of vacuum are used to seal the jar in the first place.

Chris

 

[wood-of-1kind]

Chris(Cowboy), thanks for the reassurance that the large glass jar does work. I'll see if I can score one from our cafeteria. Will try to stay around 20" of vac and see how it works.

-Peter-

 

[Cowboy]

So I turned the first two redwood burl pens that I stabilized tonight. The top is CA finish and the bottom is PPP:

It was a little harder than plain redwood, but it was still pretty soft. I am confident that at least the solvent got all the way though since it had a slight odor during turning. I used minwax poly cut 50% with mineral spirits. It was not where near as hard a a commercially stabilized pen blank, should it be? What should I try for my next set? Different liquid? How about lacquer? Let it sit under a vacuum for a few days? More cycles? Soliciting all input.

Chris