Hello everyone! 
I recently posted a topic regarding a bridging issue we were experiencing with an infused carbon fiber part (http://www.talkcomposites.com/25379/Carbon-Fiber-Lifting-Off-Mould). Hanaldo gave some great advice and suggested that we work on positioning the bag more effectively before achieving a complete vacuum. So we worked on that and performed another infusion with 3 layers or 200gsm carbon and 2 layers of soric in between. We pulled the vacuum slowly, positioning the bag, and pressing the layers firmly into the corner of the mold. The end result was a substantial improvement. However, some bridging persists. Please refer to the photos attached below. Additionally, we also have a new issue: The soric is printing through the carbon quite a bit. I believe this might have been a curing issue as the temperature might have been too low. I should mention that we are allowing the vacuum to run for several hours after the part has been infused. This has not created an issue for us in previous parts but might be something for us to consider.

Any suggestions on how to completely eliminate the bridging issue and the soric print through are much appreciated.

***Photo of bagging during infusion:

***Photo of Bridging:

***Photo of Soric print through:

Yeh, I agree with both of oekmonts points.

Your issues with bridging are definitely stemming from how you are laying up, that is far too rigid a laminate stack to get enough movement with all the layers tacked together flat. You will find it much easier to simply place the layers in one by one, relatively loosely and just held roughly in place by a piece of tape. This would be more to prevent the layers falling off that vertical edge than anything else. Don't use any spray tack at all, in this case it is hindering you rather than helping you. Then you use the vacuum bag under partial vacuum to position everything fully.

You should have an idea now how much resin the part wants, but I would suggest working it out regardless. Just measure and multiply the length and width of your carbon to work out it's square meterage, then multiply that number by the weight in grams your fabric is, and finally divide that by 1.5 to get your resin ratio. So for example your carbon is a 200g measuring 500mm x 200mm then you do:

(0.5x0.2) x 200 = 20g
20g/1.5 = 13.33. 

So in that scenario, each layer of carbon would want 13.5g of carbon, so if you have 4 layers of carbon then they need 54g of resin. Do this for each different weight of fabric you are using, and then for the Soric it is simply 550g per square metre per mm thickness. So if you have 2 layers of 2mm thick Soric, each measuring 500 x 200, then you need 110g of resin for that, plus your resin for the carbon. And if you are using any flow mesh, this uses 700g per square metre. Then factor in 10% wastage on top of that.


This will generally give you more resin than you need due to the wastage factor, but not by much. So you can afford to make it a little more resin rich if you are wanting a perfect surface finish, or you can just clamp when the resin has totally wet out the laminate.

As Oekmont has said, you need a perfectly sealed bag, there's no.point leaving the vacuum on. The only time you can do this is if you are double bagging, and then you would clamp the resin outlet from the part but leave the outer bag under active vacuum. But it is better to just get a leak free bag.