How to make bags for vaccum bagging? - RC Groups
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Dec 23, 2009, 11:03 PM
Registered User

How to make bags for vaccum bagging?


I am building my vaccum pump to make my first set of sheeted wings. I have not been able to find a good link so far explaning how to make the bags. I bought some 4 mil drop cloth and I was wondering how I should proceed to seal it. I have read that people have used packaging tape to close it. Also, what do you use to connect the vaccum hose? Can somebody explain to me how to make the bags?

Merry Christmas,

Le fou
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Dec 23, 2009, 11:25 PM
Red Merle ALES
Curtis Suter's Avatar
Le fou,

Window caulk comes to mind. Make sure when you apply the caulk between the mylar you roll it out and anywhere there is a crease will leak. It's hard to get a good seal, but you can do it, it just takes some practice.

The best way to go is to purchase a bag that's actually a tube, so you only have to seal two sides instead of three!

Here's a company in the USA that has some tips/ideas for you:

The first item is Quick Lock Vacuum seals work great. Sometimes I have to double the plastic over prior to clipping them in but they seal real well.

For the connector see the fourth item down the list.

If you search in this forum you can also get ideas on how to make your own vacuum bag connector and also the bag clips.

Merrry Christmas

"A Beginner's Guide to Cutting and Bagging Foam Wings" DVD might interest you too.
Dec 24, 2009, 02:00 AM
Not landing late ever again
threcixty's Avatar
Sounds X rated, but "tons of cock.. caulk.. whatever." Make a sheet double the size that you want, do you layup on top of one layer, fold the other layer over, add caulking (whichever is cheapest at the time) to seal the bag. Punch a hole the size of a vacuum tube, add a bunch of paper towels to the inside of the bag where the tube ends at, and pull vacuum.

You could also buy some stuff from CST or ACP with bag clips that mae it really easy. I'm lazy, so I choose that route.

Dec 26, 2009, 11:09 PM
Registered User
ozmo01's Avatar

inexperienced answer

I am geting ready to jump into vac bagging also. I have never done it BUT I have been busy doing my homework! Mostly here. I found very nice clear vinyl material at Wal-Mart in the fabric section. Different thicknesses available and Cheap. Used for making clear slip covers for furniture. They also have dress liner(aka peal ply) and backing material (aka breather).
A video of some professionals doing a bagging used white silicone caulk on what looked like 6mil on two side leaving an end open. they closed the open end with a clip I think. You can buy the clips at CTS and the like. Removable window caulking that comes in roll can also be used for closing the end and packing around the vac line. Do a few searches here there is LOADS of very good info.
Good Luck
Dec 26, 2009, 11:22 PM
The Junk Man
I buy clear vinyl shower curtains at Wally World for 95 cents each on sale. Glue them up with HH-66 and done. They are 6 mil, and you even get three cheap magnets out of each one.

Dec 27, 2009, 02:47 PM
Just fly it!
wyowindworks's Avatar
It's pretty tough to beat these and these. No caulking and farting around. I think that it's also cheaper in the long run.

Another option is use Poly tube stock and seal the ends with this....or use regular bag clips.

Dec 28, 2009, 05:40 AM
Registered User
soarluck's Avatar
Last yr around this time I started vacuum bagging and cutting foam etc.
I went from puddy to soldering iron to carriage bolts and more puddy and every few wings I could afford a BIT of a up grade.

I have come full circle in terms of different systems from aquarium pumps to fridge pumps .
I dont regret ANY of it BUT I would have rather spent the time the first time around and just bought proper plastic with the clips .

Dont skimp on some of the items just to save a few bucks ..The plastic tubes from cst are great . Far less leaks/aka BS than poly and will stand some heat also.
The bag clips are also well worth the money.

Dont spend your time chasing leaks . Your savings will be better spent repairing for the lay-up in other ways .

Dec 31, 2009, 07:59 PM
Registered User
After hours of chasing leaks, I have a few thoughts.

The plastic c clips really don't work well. Even doubling them sometimes doesn't help.

I finally ended up caulking one end of the bag. Where the inlet is. I caulk the other end and also use a c-clip. Doesn't really help, but makes me feel better.

The thing that causes the most problem for me, is the tube connection. I'm using something from CST that looks like a tubeless tire stem. The problem seems to be that the bag they cell will wrinkle when trying to get it tight.

The next thing I'll try is to get a bag sealer that will take a bigger bag, perhaps like Aircraft Spruce sells. Just make the bags long, and reseal on end as needed. When it gets too short, do another bag. If I had Adams sealing tool that he uses for bladders, I'd just use that.

If anyone has a foolproof inlet method, I'd like to hear it.

Dec 31, 2009, 08:42 PM
Registered User
soarluck's Avatar
lol Nothing is fool proof in vacuum bagging but I have just started using this item and found it to work well..Its built very strong and the twisting that you place on it pushes down yet not around . Its CAM that pulls the flanges together. I could help seal it with oil I think also because the seat looks like leather but I have not need to

Jan 01, 2010, 04:40 AM
Just fly it!
wyowindworks's Avatar
I just simply quite caring about bag leaks. My bags leak.....and I'm o.k. with that.

My parts still come out nice.
Jan 01, 2010, 07:35 AM
Registered User
I use thin polyethylene film sock, so the edges are already sealed. For ends I use cheap homemade clips:

Basically round wooden stick and slightly undersized plastic U-channel. Got them from hardware store. The plastic channel is used for framing the edges of the wall panels or something like this.

I roll the end of the bag 3-4 times around the wooden stick and then push it into the plastic clip. The two big paperclips make sure that the stick does not pop out from then channel.

The thin LDPE (low density polyethylene - the stretchy stuff) sock can be damaged easily - I replace it after two or three baggings. Recently I got some thin HDPE (high density PE - non stretchy PE) bags that might be better, but I haven't tried them yet.

Jan 02, 2010, 11:44 PM
Not landing late ever again
threcixty's Avatar
Thanks Arne!

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