How do I get vacuum from a pump into a jar cheaply?

So, I've recently got it in my mind that I want to stabilize some wood with resin. The basic process is to submerge the wood in resin, apply vacuum to get all the air out, then release vacuum or even apply pressure. Vacuum can be applied relatively quickly, but the wood must be left under vacuum for a significant amount of time. In order to have many batches going at once, I want to be able to use mason jars.

With $50 of brass fittings, this seems easy enough to accomplish, but if anyone knows a cheaper way, I figure it's the good folks on this forum. Will push fittings and plastic tubing work? Where is a good place to get the fittings without getting nickel and dimed to death? I tried a local Lowe's and didn't see any good options for a bulkhead fitting for the lid in particular, or a way to have a releasable valve. I've thought about just putting a whole jar in a vacuum chamber and hoping the lid seals when I release the vacuum, but this seems less than ideal because there's no way to check how much vacuum is being applied and getting the lid off could be a problem.

There's a food saver attachment for mason jars. Think they're $20 new.  I do think you'd need an adapter to hook it up a bigger pump.

In my experience, my food saver caps at about 5inhg, where my standalone pump goes to 27.5

For $150 or so i bought a single stage pump and 3 gallon chamber, but I could understand wanting more smaller containers

Finding a jar big enough to put a vacuum in is the trick....

Is 23 inches of Mercury enough vacuum?

HF air vacuum that is cheaper than a mityvac

Those air powered vacuums work fast, but will not suck down as far as a pump.

If you heat the jars with the lid loose and then let them cool they develop vscuum. Isn't that how canning works?

Ummm, you must have small pieces of wood if you are trying to do this in a canning jar.  Maybe do more pieces at a time in a pressure cooker?  Just what are you trying to stabilize here?  Pistol grips?  Chess pieces?  Shift knobs?

More information would probably help.

My brain can't get past getting a vacuum "into" a jar.  

IIRC you can get ABS or PVC lids for mason jars.  Then it's just a matter of drilling a hole and gluing in plumbing fittings.

Stampie (FS) said:

My brain can't get past getting a vacuum "into" a jar. 

Adding vacuum to a jar is just like adding lightness to a race car.

I would find an old AC vac on CL and epoxy some fittings to the lid. Once the process is done the vac will be lost when you disconnect the vac pump.

Look at vacuum bagging supplies from the composites folks like Aircraft Spruce or Fiberglast.  They have plastic fittings and tubing that work for vacuum.  The fittings for a bag could be used as the 'bulkhead' fitting in the lid of a mason jar (comes with an o-ring and a nut to hold it in place).  Can a glass jar really take the vacuum without breaking?  

I think he's on the right track with a rigid container.  A bag is great for laminating where you're using air pressure to squeeze the layers together and minimizing air, but in a situation where you need to pull a vacuum on a liquid resin for a long time, I don't think it will work.  Ever try to use a FoodSaver to vacuum seal a bag of tomato sauce?  Not pretty.  The air pressure just pushes the liquid out of the bag and into the vacuum.

bearmtnmartin (Forum Supporter) said:

If you heat the jars with the lid loose and then let them cool they develop vscuum. Isn't that how canning works?

That works because the water inside the jar evaporates and displaces the air.  Then when it cools, the water condenses forming the vacuum.  Without water I'm not sure if it would create any/enough vacuum.

How about a threaded schrader valve with the valve removed?  Many A/C vacuum pumps come with adapters for threaded fittings to do R12 systems.

But nearly any bulkhead type fitting can be found in the plumbing repair aisle at a blue or orange store.

Kubotai said:

 Can a glass jar really take the vacuum without breaking?  

Good question.  Canning works because the can is usually filled with liquid which can't compress, although it could displace into the vacuum space above it.

I wonder how much vacuum canning provides.

Yes, glass jars can take it. Maybe not indefinitely, but they can.

A good homemade vacuum system I've seen uses a giant glass pickle jar for the container, and the nicer chambers have glass lids, albeit thick ones.

Worst case, it implodes, embedding the glass into the piece.

What you want is FoodSaver T03-0006-02P regular jar sealer. It's a ball jar lid that's designed to be vacuum sealed. Unfortunately it's unavailable on Amazon right now but you might find it elsewhere. They make other sizes too. 

In reply to RevRico :

Do you think the food saver attachment would be happy at higher vacuum? Do you think a regular mason jar lid would be able to take it without being screwed down?

The trouble with a large chamber is that I would need to fill it with an equally large amount of resin. At about $100/gallon, that wouldn't be cheap. Also, various wood species tend to color said resin, so I try to keep species separate from one another.

In reply to Trent :

I actually already have the single stage harbor freight vacuum pump.

In reply to noddaz :

I am trying to stabilize wood for knife handles, primarily, but I would likely also make other things with the wood starting with shift knobs and jewelery. Some of the wood will fit into quart sized jars, but half gallon jars seem to be a much more workable size.

In reply to Stampie (FS) :

That's a poor choice of phrasing, isn't it? In reality I want to get virtually all the air out of the jar.

A plastic lid is a good idea. I have no problem drilling into a metal lid, but plastic could be a better solution.

In reply to Kubotai :

That was a great tip. There are definitely some of the right fittings available, although they're expensive.

In reply to white_fly :

I use platinum cure silicone, I know all about expensive stuff in the vacuum chambers. $200/gallon. 

I've used my foodsaver mason jar attachment on my vacuum pump, I was wrong, it was just brute force that got it on the nipple on the pump. I haven't kept vacuum on them for very long, just screwing around with marshmallows to show the kids about vacuum.

Maybe check your local good will or restore/habitat for humanity for a cheap used one before buying a new one just to test.

I just flipped through Amazon looking for something else, and they have 1 and 2 quart metal containers with plexi lids with fittings and gauges, they're just $40 each. This one If I can get the time today I'll see if I can fit mason jars in my chamber. I run 4, 16oz cups at a time in my 3 gallon, you could, with a tall enough chamber, run multiple jars inside the chamber without lids on them to do multiple batches are once.

There's a couple of wood workers on my discord channel I'll try to ask too. 

In reply to Curtis73 (Forum Supporter) :

I looked for Schrader valve to npt adapters and didn't find anything, but I'm going to keep looking. Schrader valves are so cheap that it seems like a great choice.

In reply to RevRico :

Thanks for all the feedback, and please keep it coming. My current setup is a metal chamber with an open top container set inside it. It works well, but I just can't get it out of my head that a better and more modular option must exist. 

Also, apparently plexiglass lids have had trouble with both cracking and becoming cloudy when used with the resin I use.

bentwrench said:

Those air powered vacuums work fast, but will not suck down as far as a pump.

For sure, but an Airlift will pull over 28 inches of vacuum on a cooling system.

It also requires a LOT of air volume to do it.  If you don't have a 60 gallon tank and a high volume compressor to keep the pressure up, you're better off with a pump.