cheap vac bagging mastic

General Discussion
1

hi crew

just throught I would pass on a tip for cheap vac bagging mastic in case some of you havent used it.

Just get the cheapest tube of silicon from the local hadware shop and run a healthy bead around between the palastic sheet then squeeze up. It dosent have to set or dry and seals better than the 20 dollar roll of bagging tape and is way easier than trying to tape up a bag.

Only down side is that it is a bit messy.

cheers

2

that’s a good one.

I can visualise it.

Plan to use it soon, thanks!

3

Another potential downside - silicon doesn’t stick to anything, and its presence could cause problems with laminations bonding properly. At Hydro Epic, if we even had an open tube of silicone near the finish area, we’d get problems painting the boards. Silicone was totally banned from our shop. I’d worry about silicone particles finding their way into the bag and screwing up your hard work.

4

Hey Kendall,

that’s a good point! Silicone does wierd things to our composites, one of the worst contaminants

right up there with oil and grease.

Maybe a water-based latex would do well? out of a caulking gun?

Lately I’ve been bagging bigger and bigger projects. When I worked in the aerospace industry we

used two sheets but with double-sided tape on large composite inter-stage sections. A liquid sealer

would be great, as I could set my work onto one sheet, place another over the work, then lay a bead all

the way around (away from the board). Flow and migration of the sealer would be a concern.

just a thought…

5

Agree with Kendal about the silicone. I’m just so reluctant to even have it in the shop cause it can cause so many problems. But the concept is good. I use a spray adhesive to seal the edges of the plastic bag. It’s used for sealing tyvek -the stuff they use for wrapping houses.

One day I was walking down to check the surf after struggling to get a good seal on a vacuum bag. There was a full can of this stuff on the walkway. It’s brilliant stuff. Seals well for vacuum but you can pull the edges apart pretty easily if you want.

If you wanted to use a tube of something - how about acrylic caulk. Seems like it would seal just as well as silicone without the contamination issues. Probably cheaper too.

6

ignorance is bliss, didnt even know silicon was a problem and havent been any issues that i am aware of in all the times I have used it (only 12 or so).

Its funny though roof silicon sticks/seals almost anything on the gutters etc.

Might try a mastic, or what about liquid nails all the same principle gooie sticky stuff. The spray adhesives a good idea.

cheers

7

I havent had any problems with the sealer flowing in towards the job, I lay up the job on the plastic sheet with appropriate beathers then run a bead on three sides and fold the bag over run around the edges pressing together and hey presto sealed bag.

will now have to look for less contaminating stuff to use, preferably in a caulking gun as its too easy to apply

Any suggestions?

8

Try a product called Lexel to avoid silicone issues maybe.

http://www.sashcosealants.com/products/hi/Lexel-4-Pak-P1C0.aspx

9

Just use 2" masking tape, at the levels of vacuum used making boards, it is as good as anything else and cheap too!

10

Vinyl cement.

11

Why use consumables?

Quote:

QUICK LOCK SEALS

A quick, convenient, innovative method of sealing the nylon bagging tube exclusively from ACP. Eliminates the need for vacuum bagging tape, allows easy access and insertion of the wing into the bag and allows repeated useage of the bag tube. Available for the 18" and 36" 2 mil nylon bag tubes.

http://www.acp-composites.com/acp-vbes.htm

Edit: $7 for a 40" seal. That’s hardly more than a tube of silicon. Mine have lasted at least 40 uses & counting…

12

I followed the suggestions of Bert Berger’s now venerable vacuum bagging thread and used masking tape to great effect. “Multi purpose adhesion stripping” is what he called it. Worked great (with Home Depot 4 mil plastic sheeting). What could be cheaper?

13

Thanks Benny, thats the stuff i have been looking for, just cant find it at local FG shops here in west Oz, looked at using electrical condute but was worried about sharp edges. I have also used 6mm groove routered into my rocker table and then plastic held down with fly screen rubber stripping, that works great on rocker tables, might be able to knock something up for bags.

I have tried masking tape on a few occasions but with my low volume fridge compressor it just didnt do it, worked ok with a vac cleaner at higher volumes.

cheers