print through

General Composites Discussions Composites Talk
#1

im getting a problem with fabric printing through on infusions,i think this is because im infusing into an empty mold,ie no gelcoat or duratec.i can cover it a little with clearcote but its not ideal.im also noticing that the fabric is getting a bit squashed,the weave is slightly rounded.i know these arent huge problems and 99% of people would never notice but i would like to eliminate it,is progressing to spraying a base coat of something into the mold my only answer?? you can see the print on the 4x4 twill on this part(cheers baz!)

#2

You mean print through as in a buch of small pits?

I was always under the imprssion that those were due to resin shrinkage and low pressure while the part is curing.

#3

What also happens if it was a 2,3, 4 etc part mold? and the line where both parts meet arent perfect… spraying duratec/clear… how would u fix that after?

#4

Print through is when the texture of the carbon fiber can be felt after the part is cured. I would expect that spraying duratec in a negative mold before infusion would fix this problem. Best to ask one of the professionals on this forum first though…

#5

you cant feel the weave and there are no holes but if you hold the part at an angle you can clearly see the weave on the surface,its virtually impossible to take a pic of this though,you can just about see it in the above pic.

#6

here you go,gotta love my new nikon d80 :slight_smile: you can clearly see the weave at this angle though looking directly at it you cant see it and you cant feel it,this is print thru.

#7

What kind of release agent are you using?

#8

Thats not print through, but rather resin starvation in the voids. Could it be that these areas are beginning to gel or kick before the others ?
If so…evn if you clear gelcoat…this will show up as a bubble or air void…since the gelcoat simply mirrors the mold surfaces.
You may need to preheat your mold under surface prior to unclamping your feed line so the resin flows out better.
You’ll find that the voids may fill better.
Best of luck .Vinny

#9

hmm,well im not convinced lol,there is no air there and from 90% of angles you cant see anything wrong with the part at all,i am using mquiars release wax,no pva and heating both the mold and resin before and dring the infusion,which takes about 4 minutes using epoxy thats taking about an hour to gel.

#10

you can do nothing about it. Every flat panel I make that has no gel and with epoxy does the exact thing. The only thing you can do is shoot a clear or duratec. Most of my customers like it that way rather then with a clear. As far as it being squashed. With infusion you are majorly pressing your carbon to the mold it is going to get squashed. At SEMA you could tell what parts were bagged or infused and what was open molded by just looking at the fabric.

#11

thanks for that :slight_smile: so duratec will cure the print but not the squashing?

#12

Can i ask, Whats the best steps to put duratec in a 2-4 piece mold? the lines that seperate the molds will show? i guess sand down and then shot 1 more thin layer of clear? also, is the Duratec 904-040 clear does it have any UV protection?

is it better to spray the part AFTER it comes out of the mold? i would think inside the mold b/c of the parting lines. you’ll atleast have time for sanding before hitting the fibers. correct?

Ive also been reading. how is Duratec used? mixed in with another gel coat?
Is there a product line that is clear, uv protected, can be sprayed either from a can, and isnt hard to just mix???

#13

i need all those answers also lol :slight_smile:

#14

haha =) lol

#15

Duratec is a Revchem product and you might find some answers at www.revchem.com and tell them you read about them on here…

The Duratec I’m using in the classroom is a clear PER Gel coat.

#16

Can you give me some details. Its a 2 part system? 1:1?? sprayed with? can i use a touch up gun to spray it? how long does it take to set. can it work with epoxy layed on it right after its dry. (i think it can since ive been reading on the board)
uv protection?
thanx!

#17

When you pull the part, is there a slight mirror image of the “dry spots” in the face of the mold? I was building some parts at one time without any type of clear gel or topcoat and was using a paste wax as a release agent- much like you are doing now. Had the same results you are experiencing. I switched to using Frekote FMS to seal my molds and WOLO as the release and never had the problem again.I thought it might have been some spots were being pressed down harder than others and “eating” though the wax, barely sticking to the mold- making the spots.

#18

yes there is a matching pattern on the mold…i will investigate further!

#19

well theres a surprise,not a single uk supplier!

#20

Duratec UK importer is somewhere in Essex, but you get it from Polyfibre.

k