I've identified one of my oversights, butyl tape is not very sticky in my cold a$$ shop!

This is anecdotal info, but just in case anybody is thinking about doing any vac bagging for any purpose, the black butyl tape is not sticky enough for cool temps. The grey tape is stickier but I ended up making this seam roller so I could get the stuff bonded to the form and the film. They make a yellow butyl tape that is supposed to be extra gooey, it's probably what I should be using in my shop in the winter. Learning something new
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I used the black tape around the exhaust tubes, it really going to suck getting that out of there
The pipe is my amplifying tube for pinpointing leaks. It helps, but some type of leak detector would be priceless right now.
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Mechanics stethoscope? Works for water.

I had the same thought fly
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I even attached a cup on the end. Didn't work either way. It does not seem to pick up sound waves from air movement. I put it on an identified, big leak and got nothing

Now I'm sitting around trying to figure out if I can inject some silicone or caulk as a stop gap. It's going to be a big mess if I have to re-bag

Let me first say, I'm not trying to be an arse.

But couldn't you just move the form to a warmer in environment to allow the tape to regain its sticky quality?

Also, can you put low pressure on the bag and just do a smoke check for leaks?

Heck no Bvas, I appreciate any ideas. I wish the sticky issue was the only one, but I did a sloppy first time job on this, so I'm fighting my own ignorance more than anything. Smoke check is a good idea and I have a smoke generator for checking auto vacuum leaks, but it burns mineral oil and I am concerned about contaminating the materials?
I was checking out these ultrasonic leak detectors they make for vacuum and pressure, but even the cheap ones are spendy and then I have to wait for it. Have to decide if this is the way I want to do this going forward and is the detector worthwhile. Most of these leaks would be of no concern if I was doing a glue up, but with infusion any leaks, even minuscule nano holes will cause of streak of air bubbles in the glass.

I have used a pice of small tubing (1/4" or so) without anything on either end that fits in my ear to chase leaks in a bag. Has to be quiet though and I guess a leak is more important in infusion.

I'm on my phone so can't see photos well, are you using a tube style bag around the form or sticking the plastic film to the form?

I guess that tape is a Steaming pile of Dog Poo

I figured contamination could pose a problem with smoke. That's why I wondered if you could pressurize the system instead of vacuum.

What about pressurizing the bag with air and checking with soap and water on the outside. 

Fly, the tube is what I have been using. Wanted to try the film out as it uses a lot less plastic. On the other hand it uses a whole lot of butyl. Maybe its a wash?

Quote from: Bvas on January 17, 2022, 06:06:24 PM
I figured contamination could pose a problem with smoke. That's why I wondered if you could pressurize the system instead of vacuum.

Thats funny because the first thing I did was blow some smoke at the bag before it dawned on me that I would never be able to see it inside that compressed mass I'm scared to put the smoke in either way

I don't want anybody to think I am blaming this on the tape, it may have its limitations, but this was operator error.
I am glad the thread title fits now

Rawhide, I wish I could do that, but it would contaminate all the materials inside.

I did have an idea. So I put the bag under vacuum and I filled a couple trouble areas with this flowable silicone. I'm thinking the vacuum should pull the liquid into the the gaps. Going to let it cure and see what happened. Fingers crossed.

That was kinda gonna be my next suggestion. To swab the trouble areas with contact cement while under vacuum.

Flem alert, Flem alert....

  When I make a bag I use duct tape...  I stagger the edge of the plastic on the two open sides clamp the plastic on two ends so that it lays flat and just put the tape over where the plastic is staggered...  Works like a charm for me... 

   As for finding leaks it needs to be quiet so I have a long tube going to my pump which is outside...  I run my hand over where I think I here a leak...  It usually changes in sound when your hand goes over it...

  * I am not sure how duct tape fairs if it is really cold...

Years ago when I was doing wet composite layups for RC gliders I came up with the idea of using a soldering iron to seal custom inflation bladders (essentially a long balloon). I've also used it to make vacuum bags out of vinyl drop sheet, and the good thing is that you can then weld a couple of seals for extra security.

Wondered since if you could use a funnel over a leak to narrow down the area.

  Hey, Fly... Can you explain in detail how you do it??

  Or do you have a link of a video on how it's done??

   Sounds like a great idea...

Shredd

it came about because Adam in the video below was instrumental in quite a few guys taking up bladder inflated wet seam layups (including myself), but he was using a pizza cutter that had been heated. I tried it and found it difficult to get a consistent weld (as did Adam), so I looked around my shop one day wondering what would work better and my eye fell on my soldering iron that was sitting on the bench. I tried it and it worked a charm so I posted the idea and away it went. The seam sealing is in the first few minutes so you don't have to watch the whole 14min or so.

Like everything in composite work, just because I say it worked for me, doesn't mean it'll work for you - nor will my materials/techniques necessarily work for you (and vice versa) so it might take a lot of experimenting to work it out. I had a pretty low wattage soldering iron, but that was with thin garbage bags to get into compound corners and small steps. For bags I ended up using thicker painters drop sheet and some really thick vinyl(?) which took a lot more heat, and from memory I rounded off a bolt and replaced the tip of the iron with that. You can do any shape you want, but for strait lines like bags I found it best to run it along the a low heat sink straight edge like a piece of smooth timber.

Play around with pulling v pushing, angled vs perpendicular to the bench, tip shape, heat level etc., but you should be able to get a pretty consistent weld.


https://vimeo.com/10665397

  Awesome... Thanks...

What's up Flem

Flem's sister had surgery and he is taking care of her.