resin infusion help - dry areas

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#1

i am working on infusion goalie masks. the part is made out of several layers of carbon-kevlar.

because i cannot not sand the carbon-kevlar or the kevlar will get fuzzy i have been experimenting with different types of fiberglass to put as the first layer so that i can have something that will sand.

the problem i am having is that this layer of fiberglass against the mold doesnt wet out nicely. it seems like it is dry.

i have tried several fabrics all have basically the same results. the fabrics that i have tried are:

-veil
-3 oz cloth (plain weave)
-6 oz cloth (plain weave)
-8.5 oz cloth (2x2 twill)

the veil was the better of what i tried but was near impossible for me to tuck into all the groves of my mold.

i dont have any leaks that i can find. i have a full vacuum (~28). i am convinced i have more then enough resin. i heat my resin on a radiator until it is very watery and i have been trying different amounts of hardener but nothing seems to be working??? the inside of the part feels/looks nice and wet. it is smooth to the touch.

any help would be greatly appreciated.

#2

Pics would really help. Is it the entire area dry or certain sections? What kind of flow media do you use? Also do you have a resin brake? If you don’t have a brake your not allowing any slow areas of the resin front to catch up with the faster ones.

Edit: Didn’t know if you have seen Warwick Masks http://www.warwickmaskcompany.com/ This is how they make theirs. “By combining pre-pregnated ballistic fiberglass, kevlar and carbon fiber with structural beams placed strategically throughout the mask, a stronger and stiffer mask has been achieved without adding weight. During the manufacturing process, the mask is vacuum bagged and then placed in a pressurized and heated chamber.This very expensive and time consuming process results in a completely void free shell while using only the amount of resin required.”

#3

Yes, prepreg and an autoclave is the way to go for high performance and lightweight products, but if you do not have access to these tools, you have to work with what is available.

Pics would surely help. My first guess now is a too fast infusion. Do you have a slow curing resin, which you can leave to infuse in an hour or even more or so?

#4

im using a vinyl ester resin with a non foaming mekp as a catalyst. the resin is pretty snappy though, around 15 minute gel time when warm and catalyzed at 1.5%.

im not using an flow media. it takes around 2 minutes to infuse a mask. i took pics but for some reason its not allowing me to upload them.

whats a resin break? basically what i have been doing is laying in the fabrics in my mold, bagging them, pulling vacuum, then unclamping the inlet hose with the resin. once the laminate is fully infused i clamp it back off. i leave the vacuum pump on until it is fully set.

the dry areas basically look like the first layer is not fully saturated. i dont understand why when i just infuse carbon-kevlar i dont have problems but as soon as i add one layer of fiberglass it doesnt want to infuse nicely for me.

i was hoping to be able to turn my molds twice a day so that i can keep up with production requirements.

thanks for your help guys. i appreciate the input.

#5

if your glass is a fine tight weave it will have a very low permability. the resin flows through the other laminate faster than you would want it for the fiberglass. you can try throttling your resin inlet so it infuses slower. or change your glass to a more permable weave.

#6

ive been using a 2x2 twill fiberglass. im not sure which what would be considered a looser weave? the carbon-kevlar i am infusing is also a 2x2 twill. i figured since the carbon-kevlar infused fine adding a layer of fiberglass with the same weave wouldnt make a difference. it is though.

what does throttling resin mean? how would i do it? just start infusing, clamp, unclamp, clamp???

thanks.

#7

what weight cloth? I mean to slow the resin by usually pinching the line and restricting flow.

#8

ive tried 3oz, 6 oz and 8.5 oz, and 1/2 oz veil all with the same results.

#9

You might want to try using a smaller I.D. intake tube to restrict flow.

#10

could you post photos of both infusion setup and demolded part?

#11

I think you should try throttling down or…

Since your using a very fast resin add 2 to 3 more resin lines. Try using smaller diameter but get as much as you can in as fast as you can. More time to wet out.

Also turn your vacuum down. I like to get mine nice and wet then turn the vacuum hard. Before it kicks.

You get more in your pot but… That might help fix the pin holes anyways.

Try lower vacuum when infusing and then turning it full after it’s saturated.

#12

I think you should try throttling down or…

Since your using a very fast resin add 2 to 3 more resin lines. Try using smaller diameter but get as much as you can in as fast as you can. More time to wet out.

Also turn your vacuum down. I like to get mine nice and wet then turn the vacuum hard. Before it kicks.

You get more in your pot but… That might help fix the pin holes anyways.

Try lower vacuum when infusing and then turning it full after it’s saturated.

#13

can you post a pic of the demolded part? Is it actually dry, or does it just look dry? Have you tried a clear gelcoat? this may fix the problem, if it is just cosmetic.

#14

Leave your resin line partly open until the part has kicked. What I think maybe happening is that you are sucking out too much resin. I would also not use Vail; it likes to be resin rich so is not happy in an infusion. I use small cheep plastic valves in my feed lines so that I can slow or stop my resin feed as needed. A resin break is need for you to be able to leave the inlet line open. Basically it can be a wad of roving (4 or more layers) before your vacuum line. The material doesn’t affect vacuum flow but will retard the resin flow stopping it from getting into your resin traps and line while allowing your part to fully saturate. (You will still need to have a resin trap before your pump) I will try to find time to post pictures of a resin break or tail. With a part as small as a goalie mask you might be further ahead to just wet bag it.

#15

Just like Dougie quoted, you need a resin break or I called it a breather pack (breather cloth wrapped in peel ply).

If you are using spiral wrap on your resin and vacuum lines they should be different sizes so you are not drying out your part once infused. Should be a smaller diameter on your vacuum size with a resin break.

#16

Is the veil a continuous Filament or chopped strand ?

#17

"Is the veil a continuous Filament or chopped strand ? "

It is not really either. Veil in appearance looks like a very fine, very thin mat. Its purpose is to hold resin and it is used on hand lay work to stop resin from bleeding out on vertical surfaces and on outside corners. Veils is also used for lining the insides of tanks to give a resin rich surface eliminating the possibility of the glass fibres in the structure from wicking liquid. It has no strength at all. It is not a suitable material for infusions as it needs much higher resin content than what you typically get with infused glass.

#18

There is also infusable veil, like Lantor D7760