Yes, vacuum will not move fabrics, and they will not stretch either. You will need to work them in the corners yourself. Whether you use wet bagging, or infusion.
Infuse at -1 bar (or as close as you can get) and after infusion bring the vacuum back to -0,5 bar. (29,5 Hg = 1 bar)
When wet bagging, take extra care for not creating air bubbles.
Not to thread jack here,
Herman: Why drop to .5 bar after infusion is completed? I always thought you let it cure at full (1 bar)
Ok I tried agin with poor results. I degassed the resin, used preforated peel ply and ensured there were a ton of pleats to allow the material to fit into the corners. I still had a few voids, a few pin holes, and micro bubbles. I don’t understand! I degassed, the resin was clear as glass when I brushed it on and in the mold I used a heat gun to pop any bubbles. I think my pinholes and voids near the middle of the panel are due to my vaccum “port” being right over that spot which has different angles (isnt flat). I’m going to move it to a part of the panel that is flat. I’m re trying to make a panel now and I notice that my gel coat parts in little spots I think due to the parting wax. I keep brushing over and over it but it just pulls away. When hitting it with the heat gun it just seems to magnify this effect. I ended up brushing 2 coats of clear to fill in all the voids/open spots, which caused my surface to be uneven which I am sure will be noticeable in the weave. Also this time I’m going to turn down the vac to 22 inHG. I think that on my next try I am going to spray some rattle can clear in the mold and then lay up my part. I think doing is will avoid having a thick part and battling the mold to lay down a gelcoat. Any ideas???
The area that the vaccum port sits right on top of normally.
Void and micro bubbles. This is frustrating. I wish I would of started with something a little smaller!
Also one last question the preforated/peel ply won’t work into corners like weave will. I’m always left with creases filled with resin. Is there no way around this?
I don’t know but you can always save those parts I believe. Just lightly sand, epoxy or resin, cure, sand flat, and clear entire part.
I hope you’re not throwing away your parts…
The first one I skinned, which came out like crap. I got tired of sanding it and its still sitting on my back porch. The second one I injected the voids with resin and sold it (it looked halfway decent). The third one I primed and sold, the fourth one is sitting on the back porch and the fifth one I haven’t pulled out of the mold. So I can clear the air bubbles out?
Just pulled it out of the mold, it still has bubbles. The bubbles seem to be in the second application of epoxy (after the gel coat and before I put down my first layer of carbon). The bubbles are clinging to the carbon. Doesn’t make sense because I know for a fact I popped those bubbles with m y heat gun before laying down the carbon. Is it possible that my vac pump is making these bubbles? I switched to vac bagging because I thought it would help me avoid bubbles and voids! I failed at hand lay up, I suck at vac bagging, I really don’t want to move onto infusion until I master something! Well I’m going to try spraying the clear into the mold next. First I have to fix m y mold, there was a spot I heated up too much that my lay up stuck to!
Good results in infusion are much easier. Handlayup needs a lot of experience to get good results. And I don’t want to talk about perfect results.
Write me a mail with all your materials and equipment you have and I will take a look if you can use it in infusion. If that is possible and you will work 100% by the way I tell you I promise you will get perfect results, If not I will pay the materials you wasted!
With infusion of carbon visual products, a couple of things are important:
-really good vacuum
-airtight bag
-degassed resin
-dry materials (materials can be dried by keeping them under a good vacuum (less than 20 mbar, preferably 5 mbar) for a while. Epoxy + water = gas
-MTI hose
-No bridging.
The skill to produce good quality parts moved from laminating skills, which are highly dependant on materials and just plain practice, to tayloring skills, some flow front prediction (which for smaller simple parts is not difficult, and you can always ask) and leak chasing.
The fun thing is that you can tweak things with unlimited time, and only after you are happy you mix the resin and infuse the part. So much less stressful working conditions, and a lot cleaner as well.
I would definately accept the offer of Dominik, and I am sure you will produce high quality parts using a bit of his material and help.
I have had the same poor and frustrating experiences before I came across MTI a year ago. There is no better way to produce bubble- and pinhole free appearance parts. Here is an example of my latest project: http://youtu.be/EyLHBz-2Cj8
So bottom line is I have to switch to infusion? I created a smaller mold for a smaller part and tried again with the same results. Bubbles and micro voids in the corners. Also with de-gassing, I put a small cup of resin in a glass jar with 29 pressure on it and it bubbled and then the bottom part was clear but a thin layer of bubbles on the top. How do you get these bubbles out? I’ve got about 2-3 weeks before going back to work and I won’t have time to play around with this stuff but I think when I do get time I will try infusion. Has anyone had luck with wet bagging? Seems like I can make parts just not carbon cosmetic worthy parts.
Unfortunatly, I can’t help you. I am having the same problem you are and will probably switch to infusion. It seems the atrs must be perfectly aligned and you must be a unicorn whisperer to achieve perfection with wet layup bagging. Let me know if you come up with a solution.
You may have tensions when you put layers.
Your result seems to be good on plane surfaces, the problem is in corners.
How do you put your first layer ? Do you use a spray glue ?
Be really carefull with the peel ply, be sure to not have tensions. Your bagging film must be larger (30%) than your mould.
Do you use MTI Hose for your infusion ? It can help to give you a prefect result if you are sure to not have tensions on the different layers.
I don’t think he is infusing. But you are right, there does appear to be bridging in the corners.
If you remove your epoxy or resin from your degassing chamber and the bottom is clear but the top still has bubbles then you’re not pulling enough vacuum. I had the same issue before when my chamber wasn’t sealed correctly.
Here’s how to fix this.
Here’s some tips on how to degas
Good tips sduffass. Should be added to the tips and tricks section.
Give the degassing chamber a good toss while on vacuum helps as well. My colleague is pretty aggressive on the chamber at times.
Also, a wide container degasses better than a high container.
Sparging (adding air into the resin during degassing) also helps (sounds crazy, I know). Degass while sparging for 5 minutes, then keep the vacuum on for another 10 minutes.
Adding a scotch brite on the bottom of the container helps.
Pumping the resin round helps. (perhaps the sparging idea works on the same principle: getting the resin moving)
Herman. What’s Sparging and how do you add air into the resin after it’s already inside the chamber? You’re talking about adding air into the resin directly or just letting air in the chamber?
Also for containers yeah wider ones work better, but my degassing chamber isn’t the best…
For containers though I picked up about 500 clear thin wall quart containers from a restaurant supply store. Cost me around $50 and should last me forever.