just glassed my first timber board in 4 oz cloth with fgi epoxy.
for some reason i can still see the whiteness of the cloth over the cedar.
i have no idea why. its kinda like when you draw too much resin out of the cloth and it goes dry. only i didnt do that. its quite wet. im pretty bummed about it cos it really lets the board down. could it be the cloth im using, or am i just a kook???
regards…
What I’ve found in glassing with epoxy is:
As I always use slow cure hardener, it usually takes about 10 hours to cure.
Due to a slow cure, there is a lot more time for the resin to soak into / infuse into the foam than if it were a fast cure such as 20-25 mins.
Due to the resin soaking into the foam over a long time, I was always getting a fairly dry laminate after curing.
Dry laminate basically meant that the weave was still fairly visible even after filler coating.
It basically looked like the cloth hadn’t been wetted out propery.
This occured even when I did a fairly wet laminate. (about as wet as you can go without having the glass floating in resin)
To solve this:
Do a cheater coat before laminating. This tends to soak in well
Then do your laminate
As the foam has already absorbed some resin, it won’t suck in as much when it cures as it would without the cheater coat
I know in theory this should weaken the cloth to foam bond as there is less resin penetration on the foam, but I’ve found that when using EPS, it still gets a pretty good bond.
-Cam
Never used that brand of resin, but there can be issues with the whities when using epoxy over doark colours.
a picture would help. what stage of glassing did it appear, did you notice it before or after sanding?
Blush: is a milky flim that forms on the surface if the temprature was too low when you glassed, it will stop subsequent layers bonding but you can sand through it.
Crystalization: is worse, lloks like white crystals that forms on the surface if the hymidity is high or moisture settles on the surface while it is curing (like for dew)
Ghosting: Most likerly cause of the whities is from overworking the resin and cloth, and frothing the resin up most common around the lap line where resin is pulled off the flats to saturate the hanging cloth. basically los of small air bubbles traped in the resin. You can stop this by heating the resin so its less viscous. or going over it with a heat gun this not only heats the resin but also breaks the surface tension in a hot coat to release traped air bubbles.
Out gassing: You also get problems with out gassing from the blank, espcially with woods, did you seal the blank with a sweet coat before glassing? avoid this by sealing the blank and glassing on a falling temp, the blank will contract and suck resin instead of expanding and blowing gas.
Also If you didn’t seal the bland and the wood was very pourus it could have sucked you lam dry. id you still seeing the texture of the weave after a fill coat you will probable be able to sand with out actually hitting the weave, sometimes with epoxy the resin with sort of confortm the the texture but still give you a thickenouth layer to sand it out, if not then jsut another coat of resin with solve this.
Of course is could be as simple as you’ve sanded too far and hit the weave of the cloth, if your seening the checkered patter after sanding but did not before than this is the best bet.
Or there could be a problem with the oils in the would and that brand of resin.
It could also be bad cloth, my fin halos and leash loops would always come out a little milk, not the real clear like using poly, skratched my head over that for a long while, tried every trick in the book, eventually I ran out of roving. New roving no more whities.
Could the cloth have gotten damp or been sitting around for a long while and soaked up moisture in the air?
So in summery,
*pre heat the resin a little before adding the hardner
*glass on a falling temperature
*mix resin slowly to avoid loads of air in the mix
*give the resin time to soak in to the cloth, don’t over work it
*saturate and fold laps before pulling resin off the flats
*if your sanding the hot coat and start to see a checkered patter you’ve hit the weave, don’t sand any further.
Hope that helps
Hey shifty,
I feel your pain. I have the same questions as woody, though.
What type of glass finish (silane)?
Was the wood pre-sealed? How?
What is the viscosity of your epoxy (in centipoise)? Did you use heat to lower viscosity?
Can you take pics with different light angles to show us? In other words, can you see small, silvery strands when the sun shines on it at the right angle, or is all the cloth whitish/milky? Any areas worse than others?
JSS
Havent read all the responses but fiberglass cloths are washed and finished differently. Some finishes are not very compatible with epoxy and you will get these results.
Some/many finishes like silane are compatible with many different resins including polyester and epoxy. Dont worry, we all live and learn.
Are you using S-glass?
thanks all for the great responce.
first off, im not sure what kind of cloth it was. i got it off a guy who works with a lot of epoxy/ carbon/ glass/ vacuume bagging and other composite materials.
he really knows his stuff so id say it should be ok. also i helped him take a new roll out of the box so it was new stock.
-no sealer coat was used.
-i did it in a spray booth with a controlled temp. aprox 22c.
-to maxmercy, i can see silvery white strands in the dark timber. some spots better/worse than others.
-not sure of the viscosity but ill go to work in a minute and check. ill also take some shots and work out how to upload them.
its not from sanding through the weave. it happened while glassing.
i used fast hardener. i had aprox. 1 hour of work time.
im starting to think this may have been the problem. the glass needed more time to soak up resin that may have been too thick. too cold.
this is what it looks like woody…
its standard
doesnt show up on white blanks
i used to get it all the time and i use a really runny epoxy
shows up on dark sprays and wood
practice and different techniques can do a lot to reduce and even eliminate it
dont push the resin around to much
trad poly style glassing can cause foaming
and sealing the wood first or a cheater coat helps a great deal as well
thats why i dont bother with low resin ratios on my boards
cuz they kinda look like shite
if that was a sanded area, there is your problem. does it go away when you wipe it with a solvent then come back after it dries?
Epoxy weave will show over dark colors after sanding. before any finish coat, you would need to wipe it with a rag dipped in resin just to wet the weave.
Or I could be totally mistaken.
I’ve noticed some bits of wood drink more resin than others, I use a roller to wet out the wood before laying up.
I’ve seen pics of the rest of the board and believe me, we’re talking minor details.
Oily hands touching the cloth, moisture contamination, cold resin can all contribute.
I’ve had similar stuff turn invisible with a sand to the weave, a dab of xylene/additive F (epoxy) or styrene (poly) on the affected area, then slapping on some more resin to seal it before the solvents evaporate.
Hey shifty,
Sorry for the late reply, but the silvery strands are where the resin did not saturate the cloth fully, and air is still in there. The reason it is visible is due to the differences in the index of refraction between the air and the resin/glass. The reason the glass almost totally disappears when saturated completely is that the index of refraction of the resin is close to that of the glass.
When indices of refraction of two different materials differ greatly, about 10% or less of the light gets reflected back. You are seeing those reflections manifested in the silvery strands and tiny bubbles in the pockets of the weave. They are seen more easily on a dark background for obvious reasons.
To tell you the truth, the pic didn’t look so bad. We tend to be our own worst critics…
JSS
i think your fairly well bang on the money there. the trouble is it covers the whole board, not just a patch here and there. its quite hard to see in one photograph. there is no way i could sell this board it looks so bad. just as well i have no intention to sell this board as its my first one.
thanks again…
I didn’t know that was your first! You took on quite a few challenges all at once for your first (glassing over dark wood). I’d say you did very well, and you will get better…
Have you ridden the board yet?
JSS
I think you are getting a little too nit-picky. That doesn’t look all that bad. If you look at the pro boards up close, you can still see glass. In some cases, it is all over the board. And if the pros can sell their boards, well…
stand back
Stand Back
STAND BACK!
that is a bitchin board!
That Is A BITCHIN Board.
THAT IS A BITCHIN BOARD!!!
now that we covered that.
If You do stuff perfect the first time
nobody can talk to you.
If everything was easy
everybody would be doing everything
Perfect.
Perfect is a place
where you accept
your flaws
with humility.
if it wasn’t the cloth showing
it would be something else…
wait til the next board,
what will b wrong with that sucker?
I was influenced by a group of gremmies that could find somthing wrong with any board…
how 's the cary seidler molar test?
…ambrose…
repeat after me…
This IS A Bitchin Board!
Ambrose, I hope I get to meet you one day. Thanks