Air trapped under first layer of carbon

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Air trapped under first layer of carbon

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raymonddfz	r raymonddfz posted 4 Years Ago HOT Topic Details
r Group: Forum Members Posts: 16, Visits: 235	Hi Guys, I have been making the odd pieces out of carbon and I have recently purchased a vacuum pump and a vacuum regulator to vacuum bag all the pieces I do. However, no matter what i do, I still always seem to get some air trapped and it spoils the finish. Apart from vacuum infusion as that is another process that i have to learn and some of my moulds don’t lean to being used for that process. Any thoughts on the best process I can use to try and avoid this? And if it still happens, what is the best way of removing them and bringing them back to a good finished state once the piece is finished and out of the mould ? I have a large piece to do very soon so any help would be appreciated. Thanks in advance
	Reply Like 3
Buchado	B Buchado posted 4 Years Ago HOT Post Details
B Group: Forum Members Posts: 30, Visits: 208	+x raymonddfz - 2/5/2020 11:21:45 AM Hi Guys, I have been making the odd pieces out of carbon and I have recently purchased a vacuum pump and a vacuum regulator to vacuum bag all the pieces I do. However, no matter what i do, I still always seem to get some air trapped and it spoils the finish. Apart from vacuum infusion as that is another process that i have to learn and some of my moulds don’t lean to being used for that process. Any thoughts on the best process I can use to try and avoid this? And if it still happens, what is the best way of removing them and bringing them back to a good finished state once the piece is finished and out of the mould ? I have a large piece to do very soon so any help would be appreciated. Thanks in advance Do you have pleats on your vacuum bag? This is a common issue when the bag is over stretched and can't reach the corners in order to to push the cloth into the mold, the bag bridges and cause resin pooling. Post a picture of your setup and it will be easier to help About bringing it to a good finished state, I think (not sure), that you would have to sand all the excess resin away, but then the finish of the pooled part would be different from the rest of the piece, so you would have to sand the whole part to make it uniform. Anyway, I'm new here, I'm sure someone else will come with further advice.
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Hanaldo	Hanaldo posted 4 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	Personally I find wet lay vac bagging significantly easier to do using 'wet preg' technique rather than wetting the carbon out in the mould. YouTube DIY pre-preg and you'll find a good video describing the process.
	Reply Like 5
Chris Rogers	C Chris Rogers posted 4 Years Ago HOT Post Details
C Group: Forum Members Posts: 120, Visits: 933	It's hard to get a perfect surface with wet-layup unless you use an in-mold coating. Making sure the surface ply is well rolled out with a bubble popper and that there's enough resin to fill the areas between the weave of the reinforcement and the mold surface is hard. Its really common to get air trapped between the tows of the fabric. I'm with Hanaldo on the wet-preg thing. Laying your dry fiber out on plastic (even painters plastic will do and is great for light weight material) and wetting through on a table with a squeegee then placing a second sheet of plastic over the top and using a (clean) squeegee or a fist full of peel ply to rub the top plastic down into the fiber and work all the air and excess resin out to an edge. You can then slice up the wet-preg while it is sandwiched between the two sheets of plastic with scissors or a razor-knife. It is much easier to get nice edges and to use patterns to orient ply shapes to the weave. The big up-side is that you don't have to wet through the dry fabric to get resin to the mold surface. You just have to get the air that's in there out! Pinholes (the little air pockets that are left on a porous surface) are hard to fill any way you do it and it always seems like you miss some. A clear primer can be squeegee-ed over the surface right before you spray more primer / clearcoat over the top. No matter what you'll have more sanding to do. It's really frustrating - and one reason I like infusion! Good luck!
	Reply Like 3
Hanaldo	Hanaldo posted 4 Years Ago HOT Post Details
Group: Forum Members Posts: 2.5K, Visits: 28K	+x Chris Rogers - 2/6/2020 9:45:52 PM It's hard to get a perfect surface with wet-layup unless you use an in-mold coating. Making sure the surface ply is well rolled out with a bubble popper and that there's enough resin to fill the areas between the weave of the reinforcement and the mold surface is hard. Its really common to get air trapped between the tows of the fabric. I'm with Hanaldo on the wet-preg thing. Laying your dry fiber out on plastic (even painters plastic will do and is great for light weight material) and wetting through on a table with a squeegee then placing a second sheet of plastic over the top and using a (clean) squeegee or a fist full of peel ply to rub the top plastic down into the fiber and work all the air and excess resin out to an edge. You can then slice up the wet-preg while it is sandwiched between the two sheets of plastic with scissors or a razor-knife. It is much easier to get nice edges and to use patterns to orient ply shapes to the weave. The big up-side is that you don't have to wet through the dry fabric to get resin to the mold surface. You just have to get the air that's in there out! Pinholes (the little air pockets that are left on a porous surface) are hard to fill any way you do it and it always seems like you miss some. A clear primer can be squeegee-ed over the surface right before you spray more primer / clearcoat over the top. No matter what you'll have more sanding to do. It's really frustrating - and one reason I like infusion! Good luck! You can also allow the wet out material to cure for a bit before removing the plastic and applying it to the mould, making it a much cleaner process and getting some of the benefits of pre-preg like using the tack of the material to stick it to the mould and not worry too much about bridging. I like to do the first layer into the mould a bit early, so not quite b-staged and still fairly wet. On a complex mould I will then debulk this under vacuum until it has b-staged, so that it is firmly down against the mould surface before doing the back up plies. Keep the back up plies in the freezer to slow their cure down. Then after half an hour or so, allow them to fully b-stage before applying to the mould. I'm with Chris though, it simply has nothing on infusion and proper pre-preg. Consistency wise it is just horrible, sometimes it works quite well and you get a really nice result with very minimal issues to fix, but most of the time there are issues. So much so that I only use it for making high temp epoxy tooling, never for components.
	Reply Like 4
raymonddfz	r raymonddfz posted 4 Years Ago HOT Post Details
r Group: Forum Members Posts: 16, Visits: 235	+x Hanaldo - 2/7/2020 1:31:47 AM +x Chris Rogers - 2/6/2020 9:45:52 PM It's hard to get a perfect surface with wet-layup unless you use an in-mold coating. Making sure the surface ply is well rolled out with a bubble popper and that there's enough resin to fill the areas between the weave of the reinforcement and the mold surface is hard. Its really common to get air trapped between the tows of the fabric. I'm with Hanaldo on the wet-preg thing. Laying your dry fiber out on plastic (even painters plastic will do and is great for light weight material) and wetting through on a table with a squeegee then placing a second sheet of plastic over the top and using a (clean) squeegee or a fist full of peel ply to rub the top plastic down into the fiber and work all the air and excess resin out to an edge. You can then slice up the wet-preg while it is sandwiched between the two sheets of plastic with scissors or a razor-knife. It is much easier to get nice edges and to use patterns to orient ply shapes to the weave. The big up-side is that you don't have to wet through the dry fabric to get resin to the mold surface. You just have to get the air that's in there out! Pinholes (the little air pockets that are left on a porous surface) are hard to fill any way you do it and it always seems like you miss some. A clear primer can be squeegee-ed over the surface right before you spray more primer / clearcoat over the top. No matter what you'll have more sanding to do. It's really frustrating - and one reason I like infusion! Good luck! You can also allow the wet out material to cure for a bit before removing the plastic and applying it to the mould, making it a much cleaner process and getting some of the benefits of pre-preg like using the tack of the material to stick it to the mould and not worry too much about bridging. I like to do the first layer into the mould a bit early, so not quite b-staged and still fairly wet. On a complex mould I will then debulk this under vacuum until it has b-staged, so that it is firmly down against the mould surface before doing the back up plies. Keep the back up plies in the freezer to slow their cure down. Then after half an hour or so, allow them to fully b-stage before applying to the mould. I'm with Chris though, it simply has nothing on infusion and proper pre-preg. Consistency wise it is just horrible, sometimes it works quite well and you get a really nice result with very minimal issues to fix, but most of the time there are issues. So much so that I only use it for making high temp epoxy tooling, never for components. Thanks for your reply guys, I like them Idea of wet-preg carbon. I have a bonnet to do and I wanted to try and get an acceptable finish Without infusion so I will try this approach. Can I just ask, can you still use GC50 gel coat and do you put a coat of epoxy on first, before applying the wet-preg or do you simple prepare the carbon peel off one sheet of Plastic and then apply after the gel coat has dried. Do you also, once you have applied the first ‘wet-preg’ layer, then apply following layers of reinforcement dry and then wet out or do you have to use further layer of ‘cold’ wet-preg. I wanted to put 3-4 layers on, some foam reinforcement and then further layers to get some stiffness in the finished item. Do you then vacuum bag the whole lot or can you do it in stages ie. first 4 layers then bag, release film etc and then continue with the foam and final layers. Or do you indeed have to bag at all. I may have repeated some of your answers but just needed a bit more clarification, this is all a bit new to me but I am enjoying the experiance....
	Reply Like 2