Hank of GM gave me some of the stuff to try running through our shops wide format printer. The initial results where so-so as far as image quality. The ink would soak thru and smear on the platin. It is pretty pourous and the dot gain rendered a blurry image. This was on an aqueous based system. The image printed on the sample that Hank showed me was really crisp. My guess it was done with a solvent based printer. I'm not done experimenting with the stuff yet. Using a backing sheet helped a lot as far as bleed through. If I can slow down the passes of the inkhead to allow more drying time between passes, I may be able to improve the overall image quality. I've been ridiculously busy since the season kicked in and, I haven't had any time to test it more. The stuff is pretty interesting. Ideally the best of both worlds would be a really good graphics substrate that would also be structurally strong and light. This may be the ticket.
Finish polymer veil (nylon,polyester and now polyacronitryl or polypropylen) are used for long time for industrial part to improv finish by prevent print trough of reinforcement fiber. Laid on tacky gelcoat polymer veil make a thick resin coat that improve finish, if used with a 10% allongement resin it's a slightly elastic film strong against abrasion.
To improve gluing you need a good thickness of glue between parts, it can be difficult with porous materials like foam, veil allow this good thickness that's way it improve bond of fiber on foam. Structural glue make same thing but with far better dynamic load resistance.
Between two layers of fiberglass, veil act like a bulcker, it increase thickness of skin so it increase stiffness and thougness of parts against flexural impact stress. It's "sandwich" principle. Classic bulcker are same material than veil but thicker and full of microsphere for lightness. The new ones, honeycomb way, like soric or nidacore are lighter and acts like medium in infusion process (libtech). Corecork do the same with a green material. For higher stiffness/weight ratio we use lighter core (PVC, SAN, ACRYL foam, PP, Alu nida, Balsa...)
Those last 3 years i do many test with this principle :
What i can say is that light veil aren't the best solution to improve impact/weight ratio
Sorry for my frenglish.
Yes Lemat, It does very little to reinforce against impact.
My simple impact test was to take a 1/2" diameter metal rod, inside a piece of 3/4" PVC pipe. Drop the metal rod onto the surface being tested. This way I could accurately and repeatedly drop the rod from different heights onto differing lay-ups.
On one test, i laminated 4 oz s-cloth - 2 oz e-cloth - 4 oz s-cloth side by side with 4 oz s-cloth - 2 N-Fusion - 4 oz s-cloth. I did this onto a foam backer, as well as onto a plastic sheet with mould release, so I could have a free sample.
The pure fiberglass lay-up of the same weight was far stronger in the drop rod test than the N-Fusion sample against impact. N-fusion doesn't do much for dings.
The N-Fusion samples was far stiffer than the pure fibergalss sample. This is because by weight, N-Fusion is thicker than fiberglass. N-fusion craeates a greater seperation between the compression and tension sides. Think about it like an open web bridge. The strength comes from the bottom chord being tensioned, while the top chord is complessed. The greater the seperation of the two chords, the stronger it is.
Against a sharp impact, N-fusion does little. Against a blunt force, like your foot, it would resist denting.
Where it would have great effect, is in replacing internal stiffeners like stringers, All the stiffness wold be on the skin, and easily designed. Rather than the crude stiffiner of the wood stringer, the builder would be able to have stiffer zones.
I personally like a stiffer tail, and a less stiff nose. By applying N-Fusion between layers of fiberglass from the midpoint back, I can design the flex pattern into the board. Flex is now not just controled by thickness of the board, but by thickness of the fiberglass/ N-Fusion as well.
When i speack about flexural impact, it's infact dynamic flex stress. It's what break surfboards and more generally sandwich panel with thin skin and low density core according all university research about this subject. I first start with izod test on charpy sheep but results were not reliable because of brittleness of fiberglass so i usenow this dynamic 3 point flex test that's use for aero composits test.
I found that polymer bulcker need to be at least 1mm thick to really improve toughness compare to all glass laminate of same weight. I have far better results with thin light wood saturated with flexibilized epoxy between multiaxial glass laminate. I use a specific resin and infusion process to saturated wood and lamiante inner multiaxial aeroglass.
Sorry for my frenglish
So, let me get this straight- this cerex is the same as "skinz" which Ben Thompson has spoke about? And it is adding impact strength (preventing foot denting) and overall break strength (board snappage) but not ding resistance? Does it add this strength even in the .7 oz weight that Lost is said to be using??? And does it or does it not add overall stiffness?
It improves bond of glass to foam (Lost usage).
It provides a smooth finish (as a veil), thus reducing resin usage on fill coat? But if you sand into it fuzzes (like innegra). You better be good at bagging then! Do you think that a simple cheater coat of resin (3 oz squeegeed on) might do the same thing as a "surfacing veil" without necessitating the bag?
But, like innegra, if the strength comes from the thickness (bulker) then using a vac bag to compress the layers is counter intuitive. It defeats the purpose. This was stated by Deadshaper on the Innegra thread.
I detect three different uses- as a bonding agent between foam and glass, as a bulker between glass layers, and as a finishing veil.
How about .7 cerex(bond)-2oz innegra(bulk)- 4 oz S glass- .7 oz cerex(veil) ???
As far as I can tell, yes Skinz is the same stuff, just re-labeled. From Graphite Masters, you can buy small quantities.
Direct from the factory, you need to open an account, no cash or credit card purchases. Also buy either a left over roll from a larger run, ar an even larger run. Unless they have a left over remnant, it is a few hundred dollars minimum purchase. I opened an account, so if any of you want to split large purchases, let me know.
Yes it improves foam to laminate bond. I did one test where I put a small patch down against the foam. Put a larger patch of S-cloth over it. Vacummed and waited for cure. Lifted off a small corner under the cloth only, and started peeling. It peeled up easy, until I hit the Cerex patch, where it resisted, and then the 4 oz cloth tore before it could pull the cerex off the foam. This could be the answer to the extruded polystyrene delam problem. It has better bond than fiberglass because Cerex N-Fusion has little frayed fibers that spread out into the foam, and fiberglass. Glass on the otherhand is naturally slick. Spill some epoxy onto sheet glass, and you can peel it right off once cured.
It provides a smooth surface when used as a surface veil. Yes, and this is what the engineers at CEREX designed the product for. It doesn't use less epoxy than a standard hot coat, but instead when used under vacuum bagging it will wick the surplus epoxy from below to completely saturate itself. You will end up with a fiberfull hot coat, of perfect uniformity, that used only the epoxy that would have normally soaked into the foam below. This will require almost no sanding after cured!
I work with Fiberglass Hawaii Epoxy. Their Fast Cure Hot Coat Epoxy is much thicker than their slow cure. This keeps it from draining off during cure. Their slow cure is much thinner, and slower to cure. When your Cerex Veil surface needs its final coat, use the thinner epoxy, which flows and lays out much better than their thicker epoxy. No need for surfacing agents, just paint it on like it were paint. Slower cure, you have time. All brush marks will flow out. To gain even more painting time, you can mix several smaller batches. It won't run off like a thicker epoxy would, because you are doing a thinner coat. Your final coat will just need the lightest sanding, because it should not have brushmarks, like a thicker epoxy would retain.
At the risk of arguing with Huie Cerex Nylon 6,6 Infusion is a bulker.
As far as impact resistance vs. other properties... Consider a truss bridge across a river. It's strength comes from the top chord being in compression, while the bottom chord (the road surface) acts in tension. The cross trusses just tie the two chords together. Cerex as a bulker works the same way as the cross trusses. It makes a composite stiffer, because it seperates the two skins (chords) of the laminate. The greater the seperation, the stronger the compsite. This hepls against heel denting, because it spreads the load agross a greater area of foam. It can make select areas of a board stiffer, in the same way. You don't need to put it between layers of cloth from tip to tail, but only where you want dent resistance and stiffness. Look at Coil boards. See where the carbon hatching is? Notice the new colors in that area. Did I mention you can color dye nylon with typical clothing dye like Rit? That is an area where Coil decided to selectively stiffen the board.
Why doesn't it do much to help against sharp impact? Ever notice when a Karate demonstration breaks bricks, they seperate the bricks? That is because you are only breaking on brick at a time. It takes little more energy that way to break one brick as ten bricks, Same force, longer duration. If you seperate two layers of fiberglass cloth with a bulker, it will ding easier than if the two layers of fiberglass cloth are touching. They have a place in surfboard construction because they are lighter than both fiberglass fibers, and epoxy. Nylon is a lighter weight, far less expensive, more attractive, more abrasion resistant product than fiberglass. Better against blunt force, worse against sharp force. That is because Nylon fibers are much weaker than glass fibers. The difference in engineering terms is whether the failure was from deflection or shear.
And no, bagging doesnt defeat the purpose. Bagging creates the richest fiber content mixture.
And I disagree with the comment about innegra loosing strength by bagging. Different fibers have different properties. An individual fiber doesn't shear any easier because it is seperated from the others. It shears easier because it doesn't have the reinforcement of the other adjacent fibers. Just like the Karate bricks, take out the space, and it gets stronger, a tighter Innegra layer would be stronger.
I hope I've added a little something to the discussion.
ok so where did i say i use that particular one u and i are on far different tracks besides i started out agreeing with you
here is part of an early e mail from head office
I have supplied this before for surfboards but they had a bit
of trouble with the resin - but if you could work on it and get it right it
would be an amazing substitute for the fibreglass. Its stronger, lighter and I
so for some time now thats what i have been doing when i am finished i will post my results to them not to china
ha'' the cerex product that i have used is not a bulker cerex have a range of fabrics not all the same
the harmonics of wood fibre and nylon infused wih epoxy are so much superior to any other fabric
but to each his own usual of the rails thread
no suprise here
Yes at the risk of going off the rails...
You've made two postings on this thread, and from what I gather from them
Can you share anything about your experience using Cerex products? What was your lamination schedule, and at what weights. What was your outcome? Do you have anything that will help the rest of us make better boards?
I'm really hoping Ben Thompson will jump in here. It sounds like he has done more to understand the product, and is willing to share information than anyone. I tried to understand the excel spreadsheet he posted, but really could not follow the numbers and their values.
My mistake. If you could let me know which fabric you are testing, I'd like to know.
So back to Llibell's question. N-Fusion is a bulker, and its epoxy absorbtion is controlled by quantity of epoxy applied, and vacuum pressure.