hi guys,
i'd like to ask you if somebody has some experience with Diolen and with his look after coating.
After applying of top coat I am observing an unequal pattern or texture on surface from Diolen. Diolen fabrics itself looks good but after applying of top coat some strings of fibre
are darker than others. The more top coats the worst effect.
steps in skinning:
- black base coat then diolen
- 1st layer of top coat >>> images 1st layer.jpg
- 2nd layer of top coat + Lacquer >>> images 2nd layer

on pictures are different parts of skinned parts.
when I used only 1st layer of top coat the lines are visible but not so much.
after applying of 2nd layer the "lines" are visible too much.

Could it be a faulty Diolen product?
I tried to apply top coat with brush and also with plastic card but still with the same effect.

any help or advice is more than appreciated.
thank you very much
ondrej

Hi Ondrej,

Thanks for the post. This is a very interesting problem you have - I have never seen this effect myself also we always use diolen as a reinforcement layer rather than as cosmetic layer (where being black means that it doesn't show through as a white layer either behind a carbon fibre top layer or at the edge of the laminate when trimmed) however we would always expect that the diolen could be used as a surface layer if required.

The diolen seemed to look fine before you laminated the resin over the top. Did it still look OK after you'd applied the first coats of resin but before you wet sanded them? - If so, is there a chance that you have wet-sanded down through the top layer of diolen showing the layer underneath?

If necessary we will try to reproduce what you have there here in our workshop. Any more information you can give me would be helpful.

Please also confirm which resin you are using.

Best regards, Matt
                                                

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Dear Matt,

thank you very much for looking on my problem. Really appreciate it.
I followed steps according to your skinning tutorial video from carbonmods. But as I had this problem with darker parts from beginning I tried to wetsand first topcoat and on another try i didn't sand the first layer and result was still the same.
I used basecoat from Carbonmods and diolen cloth and epoxy resin MGS L285 (recommended by havel-composites.cz) I bought in Czech republic.
But for example I did some small car interior pieces and they are realy nice (almost as carbon). So for me it looks small skinned pieces are ok because I just cut a part of diolen cloth which was "not defected".
When I put a large piece of diolen cloth (around 90x70 cm) and laminated it I can see random dark lines on the whole lenght of cloth (here it looks for me that bundled fibers in one tow are darker from some reason than others).
I also contacted havel-composites factory but they didn't see it before so they didn't help me at all.

thank you very much for help
ondrej

Hi Ondrej,

Like Matt I have not seen this issue before but it certainly looks like defective material, it seems that some of the spools on the weft creel (each of the fibres that run down the length of the roll are fed from an individual spool) are of a different type of fibre, the more reflective material (most of the cloth) appears to look more like genuine carbon, and the darker section in lines looks like Diolen. Obviously it's difficult to tell from a photo but I cannot imagine it being caused by anything other than defective material, you will have to talk to your supplier about that, I know that this effect has never been seen on Diolen supplied by us.

The Reason that the problem becomes more obvious as you build the layers of clear-coat is the refraction from the fibres get more dramatic, i can't see how the resin could be having that discoloration effect.

I hope you get it sorted.

Paul Statham
Easy Composites / Carbon Mods - Technical

Hello Paul,

thanks a lot for help! Now we have a car in carservice, when it comes back i'll make order from easycomposites.
thank you again
have a great day!
ondrej

If you would be happy to send a small bit back we would happily look into it for you. 

As Paul said we've not seen this before but it is possible there is a fault with a batch of material we have or had in stock.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I've had a look and seems I used the last of the fabric but I do have part of the original sheet where you can see the lines. I can send this if wanted, but like I said, I doesn't really bother me, it would only be if you guys wanted to check it. I was purchased mid summer last year so chances are you onto a new batch by now anyway