I posted on here several weeks ago about my finished surface having resin voids, pinholes, and not having a good resin to fabric ratio. I do wet layup vacuum bagging. I am having issues with major resin voids and pinholes on my surface side. I have tried putting another layer of resin on my fully cured part and letting that cure. Once it has cured I noticed that it bleed through the entire carbon fiber panel. My methods I have tried are putting a layer of resin in the mold and letting tack up then laying fabric in and wetting out. Then I use perforated release film with bleeder cloth. I put that under full vacuum and leave running until cured. When the part is cured my bleeder cloth is fully saturated and I feel like too much resin is being pulled from the carbon fiber. Next method I used was wet lay the fabric and then lay it in the mold and follow my bagging process. I had the same finished product this way as well. Also, having the pinholes I try to clear coat or add a layer of resin and it bleeds completely through the panel. I am very frustrated at this point and don’t know what to do. I am ok with tiny pinholes but I want a smooth finished surface that looks presentable and where I am able to put a clear coat finish on it to make a better end result. I use west system 105 epoxy resin and 5.7oz twill carbon fiber. Would it be better to put a regulator on my pump and pull less vacuum to try and keep more resin in the fabric? Would that reduce my pinholes and cut back on print through? Any help would be greatly appreciated.
I remember your original thread about print through. I’ve never heard of a part draining epoxy that sits on the top. Can you show some pictures so we can better help ?
what release are you using?
Also have you used non-perf release film?
Pictures would be helpful
Here is a picture of the back side of the panel. The shiny part is automotive clear that bleed through the panel to the back side
Here is a picture of the back side of my panel. The shiny part shows where the automotive clear bleed through the entire panel to the back side.
Here is a picture of the front of the panel. I have already started sanding it but you can see that the clear bleed through and made piles on the finished side. This panel is only 2 layers thick of 5.7oz fabric but I have had the same issue with 4-5 layers thick. When I take the bleeder cloth off it is fully saturated. When I watch videos most people just have small circles of minor resin on the bleeder cloth. Am I pulling too much vacuum? I have never made a panel that has a smooth surface, always print through or pinholes with even small areas with no resin. I use frekote along with partall wax for my release agents. I have always used perforated release film. I started with peel ply first then release film, then I cut out the peel ply and I am still having the same results.
This is a panel right out of the mold. I tried sanding and buffing this and it has so many pinholes that the rubbing compound stayed between the weave and I can’t get it out.
This is the same panel and here are the resin voids. On the flat parts it just has pinholes all over it and print through.
i was in the same boat a few weeks ago. i used perforated release film as well. But I’ve since abandoned this method… I personally think you need to lower the vacuum. Its very deceiving as ive here anywhere from full vacuum to 10-15 (from uscomposites) which makes sense in my mind. IF youre at full vacuum until cure, the pump will just keep sucking resin out so you will get a part with resin starvation…
Another tip people kept telling me, is if you can not do a wet layup without pin holes, then your baggin will still have pin holes. apparently thats the trick, which takes a lot of practice…
Okay, here’s my thoughts… after looking at your old thread, the print through issues in that thread could be fixed by allowing a gelcoat layer of epoxy to cure until it is tact free… then start your layup.
The issue of whether you are pulling too much vacuum because videos that you saw only have a few drops on their bleeder cloth, is not how you should be deciding how much vacuum to use. I have done many vacuumed parts and the bleeder is completely saturated with resin, and I used perforated release film. So, focus on making sure that you have sufficient vacuum to press the cloth into the contours of your mold, and not on the fact that your bleeder cloth is more saturated than this guy over here. There are many factors, how much resin used, perf or non-perf film, etc. etc…
2 layer of 6.5 oz for a finished part is a very light part. It is possible for that light of a part to have areas where there are gaps between the carbon tows that are areas without any fabric. You can check this by holding the part up to the light, you may see some spots where light shines through. Usually, these spots are filled with epoxy, but perhaps sanding might have broken them open.
I’ve never seen a part bleed through like that, usually clear may roll off of the edges and migrate to parts of the back of a part, but there are parts that are darker that are not by the edge, so I’ll take your word for it that it is draining material through holes. I would suspect that the drainage is due to what I mentioned in the previous paragraph. Try using more layers, and orienting the different layers at different directions.
Pinholes are something that we all deal with. Coat on the first layer of clear with a brush, then sand it. Then you can continue spraying with clear.
I don’t understand your release agent strategy. You are using frekote (sealer or release agent, or both) along with partall wax? I’m confused because you are supposed to remove any wax from the mold to use frekote, so i’m completely lost with how you are using both together. I’m sure this is not causing your issue, but one should be eliminated to save cost in the future.
The last picture, that is just a void that can be filled with epoxy and sanded back down. Place either flash tape or release film on the epoxy and pull taught. Then after it is fully cured sand back down.
Since you have your vacuum setup, you may want to add a resin trap and give infusion a try.
Wildcard, when you say put a layer of resin in the mold and let it become tack free do I need to sand it prior to laying the fabric to make it adhere to the fabric? I ask this because I tried doing this and when I went to demold the layer of resin stayed in the mold and it delist adhere to the fabric so I have a ruined mold.
Here is my mold that I ruined where I let a layer of resin cure prior to wet laying
If you ruined a mould I would say you need to get a better release agent. What do you use? If you want a good finish you can use Marbocote fastcote or their 227ce release. Both are a wipe on and leave release so you do not need to buff them up and both will give a good cosmetic finish.
Here is a cover for some diving bottle system and it releases wonderfully…
Now for the voids and pinholes. I have done quite a lot of wet lay vacuum bagged parts but all of them have been in polyester resins. I found I could get a good part but it was variable and failure rates were too high for me making cosmetic parts. I swapped over to pre-preg because of it… But I would use a preforated release film with the least number of holes possible as it would restrict the loss of resin from the part but still allow some trapped air off the part. I also found putting some peel ply round the perimeter helped too… I would put the peel ply over the last layer on the flange area and that would help too… I always used to run a full vacuum.
I swapped to pre-preg just to save money to
be honest… OK the materials do cost more but if you do wet lay vacuum bagging you only need to have an oven and controller… The money I saved with the lower percentage of scrap parts (single digit I would say) it just made sense.
The oven can be quite simple and made using a fan heater and MDF.
Even getting the controller from ebay is cheap and accurate. I was testing mine here to see and used an old meat thermometer to check and I get it to 1 degree maximum deviation when I check it on the opposite side to the controller thermocouple and at a lower level. With parts in there the turbulance should make the oven even more accurate.
Nice setup. I"m actually gonna do this in the next week or two myself. I agree with the reliability of pre-preg, it’s worth the extra curing expense. Plus if you cure the parts at 180 or more you should be pretty covered for any normal operational temperatures. Besides, the oven controllers are not expensive and the heaters as well. The only thing I really need to invest a few more dollars in is a freezer and more bag material.
Gilbert, explain to me your release agent strategy. I don’t understand frekote and wax. Are you using sealer with the frekote? Please explain your release agent.
Morepower
I’d love to swap over to prepreg, but I have a great supplier for my epoxy, so I would probably end up paying alot more. I also mainly do large car parts and would have to construct a large oven to suit my needs, so infusion is where I’ll stay at for the near future, but I do eventually want to move to a setup like yours.
I wipe 3-4 coats or frekote on the mold drying between coats. Then I apply 1 layer of wax and polish the mold. The reason I do this is because when I only is frekote and I apply a layer of resin in my mold I have issues with it separating and fish eyeing so I don’t have a smooth coat across the mold. The wax seems to help cut back on the resin separation. I tried a sample last night where I had a small leak on my vacuum bag to cut back on vacuum because I currently do not have a regulator. It is by far the worst part I have made so far. Next question, is it better to wet the fabric out first and pay it in the mold or put the fabric in the mold dry and then wet it out with a brush? I have to find a way to have a better cosmetic finish soon because the supplies are about to break the bank. I really do appreciate the help.
Alright first off, you did use the Frekote mold sealer (frekote FMS) before you put the frekote in the mold? Because if you didn’t then your mold is still porous and that could explain the bad releases. And hopefully the 3-4 coats the frekote was just initially because you do not need to use frekote every time. You can apply a few more coats after the first pull, but after that it is semipermanent, and you can get away with multiple pulls before needing to recoat.
Okay, you should eliminate the trying to have a gelcoat layer because right now its more important to just try to get an acceptable part out of the mold. After you get the hang of that, then you should look at adding a gel layer in the future. It is possible to use a heat gun to get a first layer of epoxy to set, but right now, but in my opinion you should hold off on that until you get the other issues fixed.
If you still want to have a gelcoat layer, then it would better to just spray the mold with PVA partall instead of using the wax, but in this scenario the frekote is just wasted.
I would Brush a layer of epoxy, and then lay in my first layer of fabric. Take extra care to make sure you have it in correctly, and that it is down. Pleat where needed. After this layer is in saturate that layer, and then add subsequent layers, saturating the fabric after every new layer.
If you’ve got a well polished mould, ie. 2000 grit then polished with cutting compound, then you won’t have an issue with not sealing the mould before using the Frekote. I don’t use the sealer, I never have. I pull parts from epoxy moulds, vinyl ester moulds and polyester moulds without issue. However I always do 8 coats of the Frekote initially, then another coat between each pull.
The one thing I’m not sure about is using the wax with the Frekote. I know it’s common practice with semi perms, but I’ve never personally tried it and I have read about several people having issues with release after using Frekote with wax. Fasta could probably comment on that, I believe he does use the two together frequently. Could depend on the brand of wax too.
OP, how long are you leaving your ‘gelcoat’ layer before laying up your fabrics? If it’s delaminating, my suspicion would be that you are leaving the resin too long and not getting proper adhesion.
Hanaldo, I understand what you are saying that you can get away without the sealer if the mold is smooth enough, but with the pictures that the OP showed of the first layer of epoxy being adhered to the mold, then that suggest that the ruined mold was not to that level or did not have adequate release, which is why I suggested that he use the sealer in the future to assure that the epoxy releases.
I let the gelcoat completely cure, then I sanded it with 1000 grit to scuff it before I laid the fabric and it didn’t adhere. I am going to let it stand until tacky next time. First I need to figure out why I have a lack of resin on my finished product and why I can’t seem to get a smooth cosmetic surface side.