First Time Bagger

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First Time Bagger

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jdp530	jdp530 posted 7 Years Ago HOT Topic Details
Group: Forum Members Posts: 6, Visits: 69	I would like to ask for your help with my first vacuum bagging project. I am trying to review as many threads as I can but I would like to post my question for suggestions so I can finish project. I have written up a summary below how I built my diffuser if interested. I have a lot of pin holes and several shallow voids in finished project. I can fill and sand voids easily enough but I am trying to decide if I should spray or roll/brush a coat of thinned epoxy onto surface to fill in pin holes. I would prefer using epoxy and then I may spray an auto UV clear coat afterwards. I have never sprayed epoxy but I have thinned it with methanol which worked well for brushing on some other projects. I am not afraid of wet sanding project to get a nice finish afterwards. Thanks, I finally got around to building a diffuser for my 1990 Reynard Formula Continental race car that I run locally. I have never used carbon fiber cloth and I have limited experience with fiberglass and epoxy, but I thought I would give it a try. So I built a plug or mold out of cabinet quality 3/4 ply that I reinforced with 1x2 hardwood framing underneath. I sprayed many coats of wood-grade polyurethane which was probably a mistake. I should have used auto paint that dries faster and harder. But I finally got a 2000 grit finish on surface that looked good enough for mold surface. I laid up the cloth last week and item turned out pretty good for my first vacuum bagging project. It’s far from perfect with pin holes and several shallow voids. I guess I didn’t use a heavy enough epoxy coat initially and I should have waited for it so start setting up before I applied the first layer of cloth. I thought I got it wetted out before adding second layer. Then I used a 1/4" foam core with cutouts for several pieces of 1x2x.25 alum flat stock for mounting brackets. I punched small holes every 4-6 inches in foam since this was a large project, apprx 40”x 39”. After foam was installed I added two more layers of CF with extra strips in between to reinforce the flange at front where it will bolt to floor pan of car. I used the nylon peel ply, perforated release film, and bleeder fabric before bagging board. I spent about five hours applying glue and all the layers involved before starting vacuum. I should have used a second vacuum gauge to monitor vacuum on mold. I did have a glue trap and gauge inline from port to pump. I had a couple of minor leaks in bag but vacuum stayed at 12-15 inches. I ran the pump for six hours till midnight then I decided to shut it off because epoxy was setting up pretty well. I am satisfied with my first project that is definitely functional but I did learn from some mistakes I made that I can improve on next time. " alt="" /> Tags clearcoat pinholes Edited 7 Years Ago by jdp530
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Fasta	Fasta posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	I never use epoxies for coating like this, it's just too hard to rub back nicely. It will also run and pool making thisngs even worse and harder. A softer material is much easier for rubbing and doing nice hand work. Duratec or just more two part clear coats. Apply with a brush at first as this will push the coating material into the porosity. Fastacraft Facebook page
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jdp530	jdp530 posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 69	Fasta (07/02/2017) I never use epoxies for coating like this, it's just too hard to rub back nicely. It will also run and pool making thisngs even worse and harder. A softer material is much easier for rubbing and doing nice hand work. Duratec or just more two part clear coats. Apply with a brush at first as this will push the coating material into the porosity. Thanks for the help, Fasta! I can purchase a Sherwin Williams 2K Urethane 1 quart kit for about $45.00. I may have to find a shop to spray it for me because i would have to do it in driveway since I dont have a booth and dust would be a problem.
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Fasta	Fasta posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	Note that a professional painter is not likely used to dealing with porosity to the extent that composites often is. You could brush multiple coats yourself and rub this back ready for the painter to do a final coat? Fastacraft Facebook page Edited 7 Years Ago by Fasta
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jdp530	jdp530 posted 7 Years Ago HOT Post Details
Group: Forum Members Posts: 6, Visits: 69	Fasta (08/02/2017) Note that a professional painter is not likely used to dealing with porosity. You could brush multiple coats yourself and rub this back ready for the painter to do a final coat? I got into garage this afternoon and brushed some epoxy on a 1" border to fill in some voids and improve the edge of part. Pinholes are that bad on top side. Your idea of brushing clear-coat is a good idea, but I think I will try using some thinned epoxy first. Its actually pretty easy to sand and then I will get the part clear-coated. I built up my plug and used some 1/4x1" wood strips to help define the edge of part. This idea actually worked pretty well but I did have some low spots between foam core and hard edge that needed a little extra glue to smooth over. I took a few photos minutes ago. PS Fasta: I think I saw your ID on Composites Central earlier today. I have registered but I cannot get anyone's attention, like Canyon, to activate my account so I can post on their forum. I have emailed admin but I have not heard back in a few days now. Any suggestions? Edited 7 Years Ago by jdp530
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