Ok. It not the alligatoring im concerned with as much since i only had two small spots on the part.
Its more that once the part comes out the mold the fiber print through it very noticeable and the new issue with print through into mold surface as well.
Thats why i might try to infuse without a in mold coat and the spray the part after.
Ok,yes print through is an issue with the ester based resins. Epoxy is much much better, but with high fibre ratio processes like infusion you are always likely to get print through. There’s really only 3 ways to reduce its appearance:
Make the part more resin rich. If you’re doing a purely cosmetic part, making the part more resin rich can help. Unfortunately this doesn’t work so well with the ester based resins, as the more resin you have the more it shrinks, so you can end up getting distortion and other such issues.
Elevated temp cure. Post-curing the part while it’s in the mould really helps a lot. If you need perfect parts straight out of the mould and can’t do any clear coating afterwards then this is the best option.
Clear coat the part after it has been removed from the mould and allowed to sit for a bit of time. This is really the only way I have found to get a long lasting completely flat finish.
I will give post curing the part at elevated temp a try.
Maybe try to run the part a little more resin rich as well.
Still worried about the printing into mold surface.
Thanks for the input.
Temper the mould a few times at higher degrees. Then make few (~3-5) parts and polish the mould surface. That is the only thing that might help.
Even if you respray the problem will still be there.
Ok been busy with life and work going to get back on this project.
I prepped the mold with frekote cleaner, sealer, and release per instructions.
I tried to spray sun-shield as my in mold coat.
That didn’t go so well.
It puddled up like rain on a waxed car.
I did several light mist trying to build it up but it just keep increasing the puddles.
Looks like i will need to try a different in mold coat or not use one.
Any suggestions.
I need to go back and read through that thread on the topic to see if i can find an alternative.
Ok back to finish this project been busy with life and work.
So i prepped the mold with frekote.
Cleaner, sealer, and release as per instructions.
I tried to spray sun-shield as an in-mold coat.
It just started beading up like water on freshly waxed paint.
I sprayed it in list mist coats to start with but the more i sprayed the more it gathered into larger beads of resin on the surface.
Looks like i will need a different type in-mold coat.
Any suggestions?
Going to go reread that in-mold coat thread and see if i can find a alternative unless freekote doesn’t like being in-mold coated.
In that case i can try to infusion with my new thinner epoxy resin and see if i get a good surface to then 2k clear it.
Duratec Sunshield and Frekote work perfectly together, you just haven’t got the technique right yet.
When you spray your first 2 coats, spray them as dust coats as you said you did, but you want to allow these dust coats to set up almost completely before continuing. So as a bit of a walk-through:
2.Set your gun pressure to 50psi. Wind in the fluid control knob on your gun until you can only JUST see any material coming out of the gun at all. Spray your first coat so that you can only just see any material on the mould surface, it shouldn’t appear wet or shiny at all, it should look dusty. Allow this coat to set up for 5-10 minutes (5 minutes in 25-30 degrees, 10 minutes in 20-25 degrees).
Wind out your fluid control knob half a turn, so you can now easily see material coming out of the gun, but still not enough to give a wet coat. Spray your second dust coat in the same manner as the first, the surface should still not appear wet or shiny. Again allow this material to set up for 5-10 minutes (this is why you don’t want to mix a lot of material at the start). Spray some acetone through your gun while you’re waiting for that coat to set up so you don’t get gelling in your gun. Mix the rest of your material (I normally operate in 200ml batches depending on the size of the job).
Drop your gun pressure to 30-35psi and open your fluid control nozzle to ideal flow rate (this is normally 2 and a half turns from fully closed). Spray one quick coat so that it isn’t quite a dust coat, but also isn’t fully wet. Allow that to flash off for 2 minutes before spraying your first full wet coat.
From here you can proceed as normal until you reach your desired build thickness.
Apologies if that seems to come across like you don’t know what you’re doing or how to use a spray gun, but I do find that even experienced spray painters struggle to work with Duratec because it shouldn’t be treated like a regular paint product. Beading up of the material when used as an in-house coating is purely down to not having the right technique and not any fault of the Duratec or the Frekote. It takes a bit of practice, but once you’ve got it then it works wonderfully every time.
This is what you can expect to pull straight from the mould once you’ve got things sussed (you’re looking at the reflection off a 57 Chev dash):
Ok awesome thank you for that.
That is definitely a bit more setup on spraying the sunshield than i thought.
I was treating it to much like paint and doing mist coats and then a heavier coat using a single catalyzed cup of resin.
Breaking it up into smaller batches makes way more sense.
I will give that a go after work today.
Ok so it was a bit tricky spraying the sun-shield.
I think i need to work on my dust coats maybe.
I tried to follow your instructions as best i could.
I did the dust coats and it seemed to be going good.
Had a nice even dusty looking layer.
Its when i had to go to a medium dust coat that i think i should have done it a bit lighter and let it set up longer.
I then sprayed the heavy coat and it started to maintain and even film in some places but others it tended to bead up like before.
Here is some in order shots.
I ended up taking my fingers and smearing all the resin flat till it maintained a nice even film with no holes. I then sprayed a second heavy coat to even things out.
This seemed to save it so i let it cure for a day.
It cured nice a tack free by the next day, which allowed my to drape the carbon the mold.
I proceeded to slowly and carefully push it down into the mold trying to get it to lay perfectly flat. A little tricky but the carbon like to stick the surface so that helped it to stay in place.
Then i do two layers of fiberglass cloth.
I lay down the teflon peelply next. Hard to keep it down since its so slick.
Then goes the mesh. Still not happy with how im laying this stuff in. Abit hard to get it to flow up and down the mold surface.
Part Bagged and infused.
I need to try and use less resin next time.
Seemed like there was to much left in the green mesh layer when i demolded the part.
I used 24 ounces which seems like a lot for a part this size.
The part turned out pretty much perfect!
Thanks for all the advice and help along the way.
The frekote released amazingly easy.
Ill post a picture of the final part as soon as my phone is charged.
There will always be resin left in the mesh. If theres not you will have a big problem. Resin infusion isnt too resin efficient for small parts.
Also, I can tell you had a vacuum leak in your part. This isnt good. Make sure to do a vacuum leak check before infusion. Best to use a digital absolute pressure gauge at the resin inlet. For something like this, 0mbar/10 minutes should be sufficient.
I concur hojo, does look like there was a leak there.
Glad things worked out osburn. The Sunshield is one of my favourite products, I do highly recommend sticking with it and getting the hang of it. You’ll never look back once you do.
Yeah it sprang a leak somewhere while infusing.
Still managed to pull a good part luckily.
I will have to vac down dry longer to test for leaks.
I guess to keep to the topic of my thread.
Learned a lot along the way through experimenting and great advice from members here.
You can get pretty good result with just pure surfboard resin.
Picture of my previous attempt.
Upsides is cost, uv stable, very clear, infuses really well.
Downsides is short pot life, the mekp tends to attack the first layer if to thin, greater fiber print through once fully cured.
’
The Sunshield in mold coat with epoxy infusion.
Sunshield
Upsides is uv stable, pretty clear, cures in mold a day for infusion the next.
Downsides is cost in comparison to surfboard resin.
Epoxy resin.
Upsides is loger pot life, infuses easily, super clear, uv stable, less shrinkage.
Downsides are cost compared to surfboard resin.
I will probably stick with the using Sunshield and Epoxy resin.
They work well together and gave great results.
The cost is a bit higher but that easily offset by the benefits in my opinion.
Why do people always think about costs first? You save money with all your materials, but you make 10 parts and are still not happy with the result. Thats the wrong way. How much do you save per part by using a cheap resin? 3$ ?
A bit on the attack there.
It was more an experiment to see its feasibility.
If it worked and i achieved the results i wanted than i would save money in the long run.
This was also a learning process for me.
I have used the surfboard resin before in wet lay ups.
I was more comfortable with that plus using it was less costly if i made mistakes getting the infusion process down.
Cost savings for me would be $20 dollars for this part if i used surfboard resin. I did not make ten parts.
I made mostly test samples and two test parts.
I would probably use the surfboard resin if it where not for the fiber print through it is prone to getting when using it as an in mold coat and infusion.
About the cost factor a lot of people come in here and are scarred of the cost at first. As i was.
I don’t have a lot of extra money and want to use it wisely as i can with the knowledge i have at the time.
I learned a lot thanks to a few very helpful people that went out there way to point me in the right direction.
After gaining that knowledge i can see more clearly that now the added cost is worth it to me for certain benefits.
Its hard to have that insight to make that decision without some first hand experience and a little advice.
Some people may come to that conclusion earlier than others.
People get on here to learn, experiment, showcase, and converse with fellow composites enthusiasts/professionals.
Ended up making a laser cut bracket out of abs sheet to replicate a no longer produced factory part.
Next i need to sort out whether to add a piece of wood or plastic square in the laminate stack to screw to or just glue the bracket to the part as is.
I will do some testing tonight and see of my 2 part epoxy glue holds to the part.
Can see the results of your leak in that first photo in post #43. Void trapped between the coating and the laminate. That’s the issue with in-mould coatings, if something goes wrong then the end result is generally not fixable. So it’s less forgiving but a better result when things do go well.
I’d carry out a greater vacuum integrity test to ensure no leaks are present prior to infusing. well worth the extra time to increase the chances of a perfect moulding