What is the difference between a Build-a-Bag™ and a regular bag?
With the Build-a-Bag system, you have to adhere the stem body to the bag which takes a bit of time. The Build-a-Bag system has two closures (instead of just one on a pre-assembled bag) which means the vacuum press may run more frequently because the closures always leak a little bit of vacuum.

Can I use the Build-a-Bag kit with a vacuum press from a different company?
To use our vacuum bag with a vacuum press from another manufacturer, you may simply need to remove the existing connector on your vacuum tube and replace it with our "new" style lock-on connector.

How do I attach my vacuum tube to this bag?
Our lock-on connector is required to connect a vacuum tube to this vacuum bag. This connector is included with all of our vacuum press kits.

Do I need a top and bottom platen for the vacuum bag?
A bottom platen is required for flat panel work. Most large home centers offer 3/4" thick melamine board which works very well. The bottom platen does not need to have grooves cut into it. Breather mesh placed over the veneer panel is typically easier than using a top platen - which can be heavy and awkward. Breather mesh also makes it easier to remove glue bleed-through on the veneer.

How large should I make the bottom platen?
The platen should match the nominal size of the bag. In other words, if you have a 4' x 6' vacuum bag, then the bottom platen should be 48" x 72".

Can I put a small project in a large vacuum bag?
Yes. There is no harm using a large bag to press a small project.

If I use a large vacuum bag for a small project, do I need to seal off the unused area inside?
No. Generally speaking, there isn't much "loose" or "free" air inside the unused part of a vacuum bag. If you are using a large bag for a small project, there is not much to be gained by closing off the unused area with a secondary bag closure.

Can I press multiple projects in a single bag at the same time?
Yes. Small panels can be set side by side in a large vacuum bag. Use breather mesh over each panel instead of a top platen. You can also stack identical sized projects on top of one another if a piece of wax paper is placed between them. This will prevent glue squeeze-out from bonding the panels to each other. Be careful not to stack so many panels inside that it causes the bag seams to pull apart.

Does the vacuum bag have to stay connected to the vacuum press after full vacuum is achieved?
Yes. This is because a perfect seal on a vacuum bag is virtually impossible. Here are some things to consider...

• Sometimes the bag closure doesn't seat perfectly across the opening.
• Sometimes the bag will stretch a bit after full vacuum is created and will then need a bit of additional vacuum. This happens most often when there is a large project in the bag. The vacuum system will cycle off (if you have an auto-cycling system) and then turn on again for a few seconds. After that, it may not cycle again for several minutes or even hours.
• Old vacuum bags and ones that have been stored near sources of UV light can develop pin holes. In those cases, the vacuum press can help keep the vacuum maintained.

If the vacuum system is disconnected from the bag, you won't know if there is a leak because there is no vacuum gauge in/on the bag. With the bag connected to a vacuum press system, the vacuum level is visible on system gauge. The vacuum inside the system is the same amount of vacuum inside the bag. If the vacuum press cycles on and off frequently during a project pressing, a leak can be recognized and then fixed. However, if the leak can not be immediately repaired then at least the system can try to maintain the correct vacuum level in the bag until the panel is finished.

Does epoxy stick to this polyurethane material?
I have experimented with our polyurethane material using several brands of epoxy, and it released from the test samples without issue. However, I've have received differing opinions about this from our customers, and my guess is that it depends on the type of epoxy, how much epoxy comes in contact with the material, and how often the vacuum bag is used in this capacity.

One of our customers recently wrote...
"We're using West epoxy, and have had zero problems with the material sticking to the bags. Just pops right off. We're using it neat, and also with microfiber thickeners, and I can say there's no need to worry about sticking with West epoxy and these polyurethane bags." - Kenny Delapp, Albuquerque Joinery

Do you offer samples of this polyurethane material?
Yes. Please click here for details.

What else should I know about the bag?
The maximum project size that is listed for this bag is approximate. It may vary by one inch due to tolerances in the manufacturing process. The maximum project size also depends on the total thickness of the platen and project. The usable size of the project panel can be maximized by using breather mesh instead of a top platen. It is critically important to avoid using a platen that is too large for the bag which will cause the seams to pull apart.

Where can I find more answers to vacuum bag questions?
The JoeWoodworker FAQ page has a large section of information specifically about vacuum bags.

What is the pricing breakdown for each Build-a-Bag type?