I played around with my first vac bag setup today. I made a mold that has a tight edge that need a vacuum to avoid air pockets. For the first one I only use gelcoat/chopped strand with polyester, unwaxed. The vacuum did the job on the tight edges but I thought it came out pretty dry, the last layer looks like it had to much resin taken, some strands actually went back to being white. This may be normal I dont know, was going to ask here. I used a peel ply with breather cloth and it was under vacuum for about 45 minutes. Here a pic, any comments? Did I do something wrong? Just want to know if this is normal before I start with the carbon, its expensive stuff!
What type of pump are you using? It seems that too much resin was removed. For low pressure compaction, I have pumps that pull only 4" instead of 29" like the others.
Instead of peel ply, you can use a perforated release film to keep more resin in the laminate.
Its actually a $10 tire inflater, reversed. Ill look into the perforated release film. Would adding another layer of peel ply do anything?
what resins and fabrics did you use for the vacuum pump?
More peel ply will do nothing. Again, you’re removing too much resin by having such a porous release layer. A perforated film, instead of peel ply, will keep more resin in the layup.
What % of per and catalyst did you use?
PER will kick off in less than than 20 minutes…and if you took too long in laying it up…
I had my CSM pre cut, it took about 2 minutes to wet out, another 3 minutes to put it in the bag and tacky tap it sealed. When the vacuum came on the breather cloth was soaked in resin within about 3 seconds, and then the wet patch slowly got bigger after that. It was still very wet when the vac hit, i used 1.5% mekp. It was PER, with CSM 225/sq meter x3 with black gelcoat sprayed beforehand.
I thought peel ply is perforated, and has a release agent on it already. Whats the difference between these two product? and why are the so different? just smaller holes?
The parts seam fine tho, I cant peel back the dry layer or anything. Has anyone got a picture of the laminate after vacuum with CSM so I can compare?
peelply is a coated fabric, it allows all resin to go right through.
perforated release film, is a plastic film with tiny holes poked every square inch or 2. this way, only a little bit of resin flows through the hole.
oh ok, do I use it with the peel ply?
No, it’s used instead of peel ply. Nothing sticks to it either.
It goes directly on top of your layup.
righto, ill get some, thanks for the help.
Here is a HQ shot. Can someone confirm that the part is actually to dry and im not just making a big deal of it.
http://bigs.omfg.net.au/pics/Fiberglass/xilids/100_0240.jpg
Also one last question, when is peel ply used over the perforated film?
Some reasins are not specifically meant for work with glass. I have come across resisn that are either formulated to enhance wet out on either glass or carbon but will not give the same results when used on the other.
using csm, and since it is a random assortment of fiber in every which way it can pose a bit of a hinderance to the uniform flow of resin and bleed out of the excess resin and bubbles.
hmm ok. Im going to try a carbon layup with the peel ply today since I have a small roll of it to use up. Ill see how it turns out. Ill post pics if people are interested, otherwise I declare the problem closed. Thanks for the help.
the peel ply would be used UNDER the release film. It is meant to leave a rough finish on the part for secondary bonding.
ahhh, that makes sense. Thanks for clearing that up.