I've been trying envelope bagging recently and have decided to revert to taping my bags to the flange. With envelope bagging it's easy to set up and get a leak-free seal but I got bored of sanding resin ridges from the back of the mould and I was using twice the amount of bagging film. Has anyone else tried envelope bagging and preferred it?

Hi

I prefer envelope bagging. I'm pretty useless at doing bag pleats so got fed up trying it that way. I attach newspaper to the back of my moulds to prevent bursting the bag but I only use my moulds once so that might not be the best solution for multi use. I've not checked but I thought bag material was quite cheap compared to the gum tape? On big moulds I just cut the bag material so to leave it as a tube and then I use half the gum tape than if I had sealed it on the mould flange (if that makes sense?).

Craig

Ive done some small parts that were wet lay and bagged and kept the rear of the mould clean by simply sticking some masking tape on to it.

I too cannot for the life me get a perfect seal when I bag straight on the mold so I envelope bag.  My trick is to put a layer of breather fabric under the mold so it's softer on the bag.  Sure the excess resin finds its way to the fabric eventually but most of the time it doesn't create sharp ridges.  And it builds up after each consecutive layer of breather fabric so my mold gets thicker

Give the back of the mould a few heavy coats of PVA and this will make it easy to clean off any excess resin, if your careful you can re use the vacuum bag. 

I have only envelope bagged after spending hours trying to get a perfect seal on a mould flange in some pleat somewhere

But I should do more envelope bagging as a first option as I generally make a nice smooth wooden frame for the mould to sit so the bag would never touch the back of the mould.

---

David Stevens
YouTube: Comment | Rate | Subscribe
Instagram

Composite Projects
Body Package for Dax Rush
RC Car Touring Body 1/10 Scale

I only envelope smallish moulds ... they are all made with the EC Epoxy Putty ... I just leave any resin on the reverse side there ... Just lazy I guess ...
Usually I do not get much, if any resin on the back side of my moulds ... I sand away any sharp resin ridges, it they are a problem.

"Sapere Aude"... Dare to KNOW!

The written word is the only truly efficient vehicle for transmitting a complex concept from mind to mind...

103% of all people do not understand statistics...

Do not adjust our mind, theres a fault in reality :-)