sorry for answering so lately

I tried what you suggested and it gave a pretty good result. I sent the plates to be sprayed with automotive laquer and it looks very good.



I'm moulding bigger trays actually. I go for new adventures

Thaks again guys

Looks much better than before.  Hanaldo's tip is great for cosmetic parts, that little bit of extra resin helps reduce pinholes and gives a slightly smoother, less textured surface. 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

Looks like it's a little on the lean side of resin content. Next time you infuse, try clamping the vacuum line when the part is fully infused, wait 30 seconds to 1 minute and then clamp the resin feed line.

Hello mates

I followed your advices and did the pleats on the corners and I had good results, bubbles looks to be gone ^^
THANKS A LOT !!!



But I experiment lacks of resin now between the twills of the reinforcement... how it can be seen below. It's rough, not smooth when polishing with a microfiber which grips on it. 
I precise the mould has been sanded and polished 150 / 400 / 600 / 800/ 1000 / 1200 / 1500 / 2000 / 2500 / 3000 / 5000 / no polishing before the problem happened.


Do you think it's because of the sanding? The mould wasn't perfectly flat so I had to sand it and I'm now hesitating to spray it with automotive 2k clear coat before polishing, polishing like it is or  it s perhaps a mistake from me during the infusion? :/

Cheers

The problem I see here is that you put the pleats exactly where the aren't needed. Look at the third picture. The bag has to go through the corners without additional bagging film and therefore will be under tension. Instead of one pleat per side in the middle try two per side, one at each corner of your model.

It isn't that the pleat in the bag causes any bridging, more that if you have a large pleat in the bag then this is film that isn't in contact with your mould - so you should try to spread those large pleats across to make several smaller pleats, which means you have more bagging film in contact with the mould in that area.

Definitely getting there! I think a bit more time positioning the bagging stack and you will eliminate the bridging entirely.

thanks a lot for you precious advices

I did another infusion following the Hanaldo advices (it was before Warren replied) and I got really better results. here what I did: 




I did have A LOT less bubbles, and just a little bit on a corner (and a lot more on the exterior side on this same corner which is now cutted)
I suppose I didn't press enough the reinforcement/vaccum consommables on this corner or perhaps I should have cut the peel ply like I did for the carbon cloth and the infusion mesh...

Is it possible for this bridging to come from a fold/bend of the vacuum bagging film above a corner like on the picture (and so I should move this fold/bend on a flat surface when doing my vaccum bagging positionning)?

Thank again mates for your time 

Hanaldo is spot on here.

The simpler mould you are doing will help a little but still you need to concentrate on getting the fabric properly against the mould surface AND the bagging stack conforming too and not bridging.

I agree with taping for more complicated moulds or if you are struggling but for simple moulds like that vent, if you had enough fabric placed properly to begin with, it isn't an issue.  But yes being able to move the fabric around a little as you pull down the bag can help if things were not right to begin with.

With bagging stack, cut the mesh and peel into pieces if you need to as you can overlap bits and slide it around.  Certainly cut lines in the mesh and peel are great.

Have plenty of bag free as well.  If you've solved fabric and stack bridging you don't want to mess it up by not having enough bag! 

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

So what happened there is you still had bridging, but because you used spray adhesive the fibres were held against the mould surface and the resin has filled the gaps between the layers without the surface defects. That would indicate to me that your reinforcement layup was better, but your consumables layup had bridging in it still. So I would suggest cutting your infusion mesh at these radiuses where you have issues so that it can move around when you pull a vacuum.

I also feel like spray adhesive can hinder you with simple layups like this, because it doesn't allow anything to move around. You've got a better result here, so it may be worth trying again, but you also have the problem of it affecting your surface finish. So for me, I wouldn't use spray adhesive and just position everything loosely in the mould. Then when you pull a vacuum, draw the bag down until it is loosely against the layup and you can slide it around easily, and use this to slide the material on the flanges inwards towards the tray, and then firmly press it down into those corners. Use a blunt tool if it helps, just be careful not to damage the bagging film. This can take a lot of effort, like putting your whole bodyweight into pressing the material into the corners. It can be a workout, but on something this small it shouldn't be too hard. When you have done all the corners, pull a little more vacuum and repeat the process. Do this several times until you reach full vacuum, by which stage you should be able to put your whole bodyweight on the material in those corners and it should feel as solid as if you were pressing directly on the mould surface (because in essence you are). If you feel any 'sponginess' or can see the material move at all as you press on it then you still have bridging any you need to release the vacuum a little bit and keep repeating the process.

Easy Composites demonstrate the technique in this video at around 8 minutes in (whole thing is a useful watch if you haven't already):





The only thing I would do differently here is they used tape to hold things in place on the flanges, which I don't recommend. It does the same as using spray adhesive and can prevent you moving stuff around as much as you need to. Better to have everything loose and be able to slide things around easily.

Thank you very much for your answer, because of you, I'm on the good way:

I did another infusion yesterday using the spray tack and taking more time to put the reinforcement in position and it looks really better: no bubbles at all on the surface


The problem is the fact that the tack stay visible on the surface even after an alcohol cleaning, looks like it's inside the resin.
On this photo, I used 2 layers of polish (coarse and fine) but no sanding, perhaps it would remove it if it s still on the surface....

I still have a problem , I think I have resin between layers so same problem than the beginning but not in the cosmetic layer. I thought did it well this time but the thickness is inegal on all the edge surface. That problem is a lot more visible on 2 corners :/