finishing after infusion

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finishing after infusion

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8900120d	8900120d posted 5 Years Ago HOT Topic Details
Group: Forum Members Posts: 37, Visits: 939	Hi guys, Ive finally got the hang of making moulds and infusing. ive managed to infuse several times, however i get pin holes in the same area everytime, which makes me believe its the mould? its an automotive part, so it needs to have a nice appearance but it also needs to be protected from the elements. i have experimented with XCR : 1. apply 2 coats of XCR 2. sand down with 180 grit until smooth 3. apply 2 coats of XCR 4. sand down with 240 grit until smooth 5. apply final layer of XCR 6. sand with 400 - 800 grit 7. polish however everytime i apply a layer of XCR, by the time it becomes tacky it has loads of "craters" (see pic) it feels like a never ending process to get it smooth again and then apply another layer which again has craters when it drys! the reason why i use XCR is to get hide of the pin holes and small dry spots in the corners on the finished product but its an extremely long process! especially if i decide to sell this part. is there a quicker method of using resin clear coat which will get rid of a small amount of pin holes and dry areas? for e.g; can i apply 2 layers of XCR, sand down with 180 grit, and then spray some automotive clear coat ontop?
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Fasta	Fasta posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 468, Visits: 3.5K	+x 8900120d - 7/25/2019 12:13:58 PM Hi guys, Ive finally got the hang of making moulds and infusing. ive managed to infuse several times, however i get pin holes in the same area everytime, which makes me believe its the mould? its an automotive part, so it needs to have a nice appearance but it also needs to be protected from the elements. i have experimented with XCR : 1. apply 2 coats of XCR 2. sand down with 180 grit until smooth 3. apply 2 coats of XCR 4. sand down with 240 grit until smooth 5. apply final layer of XCR 6. sand with 400 - 800 grit 7. polish however everytime i apply a layer of XCR, by the time it becomes tacky it has loads of "craters" (see pic) it feels like a never ending process to get it smooth again and then apply another layer which again has craters when it drys! the reason why i use XCR is to get hide of the pin holes and small dry spots in the corners on the finished product but its an extremely long process! especially if i decide to sell this part. is there a quicker method of using resin clear coat which will get rid of a small amount of pin holes and dry areas? for e.g; can i apply 2 layers of XCR, sand down with 180 grit, and then spray some automotive clear coat ontop? I always do finish work with Duratec Sunshield, no craters like this and far easier to sand than any epoxy resins. Then two part clear to finish. Fastacraft Facebook page
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MarkMK	MarkMK posted 5 Years Ago Post Details
Group: Forum Members Posts: 338, Visits: 2K	If you have for a slightly porous mould, there would usually be some evidence of air ingress either during the infusion or cure. If the area in question is covered with infusion mesh during production, then you'd likely see the air bubbles in the mesh If not, it could be just your technique that needs a bit of refining. Key to getting an excellent cosmetic finish are things like making sure that the part is fully wet-out and also sections where you have corners and return consolidated to the mould surface as closely as possible. If, however, you're making sure that you parts are properly sealed and that resin is allowed to fully wet-out the part, then you'd be most likely to see evidence of bridging in corners with excess resin, rather than a broken and pin-holed surface It might not be available to your location, but the GC50 in-mould coating that EC sell is also an excellent way of giving your parts an additional coating, but it sounds like you might be best served pinning-down the root cause of your current surface issues first. If you're confident with your technique, then look for any evidence of the gel coat being broken. Quite often areas where you might have used wax seal the join between the flange material and the part can be prone to coming away from the mould during use and can be sources of leaks. In lieu of carrying out a proper repair on the mould, a little bit of wax pressed into an areas where the gel coat is missing or cracked and help seal them each time the mould is used
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8900120d	8900120d posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 37, Visits: 939	+x MarkMK - 7/26/2019 6:06:48 AM If you have for a slightly porous mould, there would usually be some evidence of air ingress either during the infusion or cure. If the area in question is covered with infusion mesh during production, then you'd likely see the air bubbles in the mesh If not, it could be just your technique that needs a bit of refining. Key to getting an excellent cosmetic finish are things like making sure that the part is fully wet-out and also sections where you have corners and return consolidated to the mould surface as closely as possible. If, however, you're making sure that you parts are properly sealed and that resin is allowed to fully wet-out the part, then you'd be most likely to see evidence of bridging in corners with excess resin, rather than a broken and pin-holed surface It might not be available to your location, but the GC50 in-mould coating that EC sell is also an excellent way of giving your parts an additional coating, but it sounds like you might be best served pinning-down the root cause of your current surface issues first. If you're confident with your technique, then look for any evidence of the gel coat being broken. Quite often areas where you might have used wax seal the join between the flange material and the part can be prone to coming away from the mould during use and can be sources of leaks. In lieu of carrying out a proper repair on the mould, a little bit of wax pressed into an areas where the gel coat is missing or cracked and help seal them each time the mould is used Thanks a lot for the replies! The layup was envelope bagged so I don’t think air got in. But I’m not really worried about the pin holes as there is such a small amount in a corner which are easily covered with XCR. My main concern is that I get loads of craters from the XCR which is increasing my finishing time immensely. I can’t seem to find the duratec product in the UK. Are there any alternatives that anyone would recommend? Thanks
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oekmont	oekmont posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 550, Visits: 27K	Tue professional way would be to not get pinholes in the first place. Usually restricting the resin flow to slow down the resin speed helps. If you got pinhole free, you could use an inmould coating polyester for a perfect finish and optimal polishing characteristics. A way to get rid of already existing pinholes is clear filler. I used a brand named basco. has to be sprayed onto the part. Fills even medium pinholes and can be sanded down like a dream. This gives the very best finish I can think of. After clearcoating of course. Epoxys like to fisheye a lot. Even the ones made for coating aren't totally free of that.
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8900120d	8900120d posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 37, Visits: 939	+x oekmont - 7/26/2019 9:04:07 AM Tue professional way would be to not get pinholes in the first place. Usually restricting the resin flow to slow down the resin speed helps. If you got pinhole free, you could use an inmould coating polyester for a perfect finish and optimal polishing characteristics. A way to get rid of already existing pinholes is clear filler. I used a brand named basco. has to be sprayed onto the part. Fills even medium pinholes and can be sanded down like a dream. This gives the very best finish I can think of. After clearcoating of course. Epoxys like to fisheye a lot. Even the ones made for coating aren't totally free of that. Thank you. I’ve never heard of an inmould coating polyester ? What does that consist of doing? Would I have to coat my mould with the polyester resin before infusing ? Would you recommend any inmould polyester resins?
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oekmont	oekmont posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 550, Visits: 27K	The one from easy composites is certainly very good. I've used this one lately. Yes, first you "paint" your mould with the gelcoat, let it cure and the proceed with your infusion setup. Keep in mind that it has to be a special epoxy compatible gelcoat. However, if you got pinholes now, you will get them with or without gelcoat. But with gelcoat, they will be under the gelcoat, wich makes it eBen worse, as you then will need to sand down the whole gelcoat to fill them.
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8900120d	8900120d posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 37, Visits: 939	Thanks a lot, I will try this. Do you normally allow the coat to become tacky first before laying the carbon fibre?
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oekmont	oekmont posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 550, Visits: 27K	No, epoxy compatible polyester gelcoats cure tack free. You have to use sprayglue like you would without gelcoat.
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8900120d	8900120d posted 5 Years Ago HOT Post Details
Group: Forum Members Posts: 37, Visits: 939	Thanks for the replies. I’ve ordered some gc50 to try out. I’m sick and tired of using XCR, every time I put a layer of XCR onto a smooth surface, it cures with craters! What could I be doing wrong?
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