Problem I had was I used an epoxy resin with medium hardener, 20-30 minutes pot life. It was a cool day, about 65 degress F, so I thought I had at least 30 minutes, but I had mixed up about 650ml. After mixing, there were a lot of bubbles so I degassed the resin for about 20 minutes. As soon as the bubbles were gone, I took the resin out of the vacuum chamber (my resin trap) and it was already hard on top so the batch was wasted. If I use a slower hardener, it won’t be as clear and I’m making a CF part with clear finish. Any tips? What products do you like?
Degas the resin and harderner not mixed. Mix with a mixing blade and make sure it stays under the top of the resin and not to fast. After mixing degase again.
Okay, I had never heard that before. Sounds like that might take a while. Do you use a slow hardener?
Are you sure that the color difference between medium and slow will actually matter to your part? Usually its not noticeable unless in extreme cases and your are comparing side by side.
Theres also plenty of other resin systems out there that are clear with longer potlife. Not sure what your making and requirements are. But Gurit prime20ULV is pretty good for standard type parts. Also Huntsman and Sika have good systems as well
Degassing your resin shouldn’t take anywhere close to 20 minutes - that’s your first problem.
Remember, low surface to mass ratio will affect pot life. In other words, if you need to maximize pot life mix your resin in a larger cup so the resin can “spread out” more.
Are you brushing/spreading the resin into your reinforcing fabrics or infusing? If you’re brushing/spreading, there’s little need to degas the resin. If infusing then you do want to degas.
Make sure your resin is mixed in cup at least twice the volume of your resin requirements before pulling a vacuum over it. Use a vacuum chamber that’s large enough for your application and ensure your vacuum pump is capable of pulling a deep vacuum (29+ inches). The resin will froth up then settle. As soon as it settles back down and no bubbles are still trapped below the surface, you’re ready to go. With the proper setup, this should take no more than a few minutes (depending on resin volume, cup size, etc).
do you guys just ignore the froth on top of the degassed resin, stick the your hose in and go?
It only takes a couple of minutes to degas the air out of appropriate resin. If it is still producing bubbles after that time, you are boiling solvent. That means your resin is not suitable for high vacuum.
A properly degassed resin won’t have any froth on top, it should be absolutely clear.
That totaly depends on the resin, mixed or not mixed, how it’s mixed, viscosity, amount, surface, temperature, ect.
Nobody here on this website infuse there products with "high"vacuum, it’s all low vacuum.
Haha maybe in physical terms it is all low vac, but given it is a composites website I think it is fair to refer to anything around 29.99mm/Hg as high vacuum - everyone knows what is meant.
Michiel,
If you want to get into semantics, I don’t measure vacuum. I measure absolute pressure. So low absolute pressure equates to high vacuum.
Are we talking about laminating or infusion resin, or some high viscosity adhesive?
Regardless of whether the resin is mixed or unmixed, or how it is mixed. Or the viscosity, or the temperature, or the size or the shape of the container, or the colour of the shirt you are wearing, if it takes 20 minutes to degas your resin, you need to find another resin supplier. It doesn’t take us that long to degas 60kg of epoxy infusion resin.
stupid question but do you just let all the bubbles go up and over your resin container without any effort in knocking them down before overflowing?
Close off the vacuum side valve and let it sit for a few minutes when it gets to the top, it will settle on its own under vacuum.
You’re not using a big enough pot if it is overflowing. You need a pot that is ATLEAST three times the volume of your resin.
Thanks guys, I now really need to degas the epoxy as am taking another process for my parts. I was planning on using an IMC but the duratec just pools up and holes (swiss cheese) over the semi-perm have tried the waxing on top of semi perm tip to but didn’t seem to help
Just gotta learn to apply it mate, Duratec works great over semi-perms.
It’s a bit different to spraying regular coatings so it can take some getting used to, but once you’ve got it sussed it’s an amazing product.
I don’t want to get in semantics, but no matter how you measure it that doesn’t change anything to your vacuum.
If you base your choice of resin depending on degassing you’re doing something wrong.
I used over 100 different resins and some degassed in a few minutes and some degassed in 1 hour. All depends on a lot of things that I mentioned before. All where injection resins or pourresins.
Twisting my words around is not helping the OP.
That is good to hear, I was just going to scrap the idea and go with a 2k clear after de molding.
Any tips you can throw at me, I tried a 1.8 tip which was to small to shoot without thinning so I went to my 2.4. Also did a nice flash/mist coat let set couple mins and tried applying thin coats to build and it just wanted to pool.
Tried the orca wax on top of the release to try to get more of a tack but same result.
Went and did full thick blast coats like you would do a clear on a car. Did not work as well.
What other factors can I try to tweak? Thanks for all your comments and thoughts I have enjoyed your posts for a couple years on here now.
I would recommend thinning 10% with pure MEK or acetone if MEK is impossible to get hold of. It doesn’t spray super well without thinning.
Also with your dust coats, let them set up much longer. Give it at least 10 minutes, probably even 15 minutes before you try to lay any heavier coats. I would recommend mixing up only 50ml or so to do that, then while it’s setting up go and clean your gun out etc so that you aren’t racing the pot-life.
Also just make sure your dust coats are nothing more than that - you want to be able to barely see it on your mould surface, you don’t want any sort of wet film on there. It isn’t like spraying an initial tack coat on a post-finished part, it needs to be nothing more than dust. Then after that has sat for 15 minutes, proceed with doing a regular tack coat, let it sit for 5-10 depending on temp, and then you can proceed with full build coats.
An important thing to note is that if you do still start to get separation occurring, don’t hit the panic button straight away. Spray a light dust cost over the fish-eyeing areas, let it sit for 5, and then proceed again. Often when you reach full build, these areas will have filled in and you will be fine.