My fin hit a rock and above the box “single fin” are hairline cracks that extends out 5 inches on each side. The fin box is still flush with the board but I guess the force from the rock cracked my gloss and maybe my hot coat. The glass is fine. Do I Dremmel the cracks and fill with the hot coat then a little gloss
Thanks
Tom
Tom,
It’s usually best to sand the whole area where the cracks are, down to the cloth. Then paint on some hotcoat, sand, then gloss an area slightly bigger than the hotcoat area.
Here’s a tip: After you’ve taped off for the gloss, and painted the gloss resin on, use a hard squeegee to feather the resin in to the tape edge. It’ll be easier to sand that pesky resin edge out later.
Doug
Thanks Doug
If you don’t want it to happen again, you might think about puting down a 4 oz patch that covers and reinforces the box. A little more taping, trimming and sanding but worth it…
I once put superglue in the cracks to keep them from leaking/Seemed to work OK.
You may not ned to sand down the the weave, sand em lightly then rub styrene on, if they disappear then you’ve sanded enough.
once youv’e taped up, before you paint resin over whole area, rub the cracks with styrene again then rub in some resin with your finger, it helps the resin get deep in to the cracks sealing them and making them disapear.
There are some good suggestions from he other guys here…I’ll just give you my take after owning the repair shop in my factory that did the vast majority of repairs in SB thru the entire 1980’s (a near monopoly as the other factories didn’t want the waxy and tarred up boards).
DS has a very thorough approach but it may be over kill. I would dremel ot around the cracks. If you are SURE the weave isn’t compromised, then all you are doing is replacing the brittle resin…cosmetic fractures disappear with styrene monomeronce they are dremeled, filed, sanded enough to wet out the area. You have narrow impact fractures so the dremel or dental tools is the right tool.
The styrene should be applied right before a laminating resin baste to enable to disappear the fractured area. Chances are if you just stick it in a hairline crack and put resin in it, that won’t work. If you apply styrene then wait too long for the resin application, the styrene boils off and will offer no benefit. Then you go about it as suggested.
As far as doing the more thorough repair which suggests sanding a wider area and capping the box with 4 oz. and masking off th gloss and taping over the box then trimming the glass.
Well…I have news for you. I developed a method for capping all my sailboard boxes (then ended up doing it on all the surfboard boxes as well) since 1980. I discovered the mesh of 4 oz can be applied right over the fin box cavity without taping. Scared? Well, I guarantee it works. Just paint some resin around the opening slot of the fin box after thoroughly sanding the area te glass is to go then lay down the cloth…wet out the slot last and swipe it with a sueegee or plastic spreader. This is very easy with UV resin but can be done with Regular catalyzed resin as well.
We would cap our sailboard boxes and adjoing woodies this way…then hotcoat, sand, gloss, polish the boards and at the very end we would open the slot cavity of the box and slightl round the sharp edges left…beautiful! No one could figure out how we were doing this early on. People asked me if we put water down inside the box first, or a foam or wood spacer…lol.
As far as “taping for you gloss coat”…why bother? If you want ease of polishing out you gloss coat to match the rest of your polished board this is the method I developed and it works quite well and saves time and money. You sand the immediate area with coarser grit (60,80, 100 grit) where you want the resin to grab and hold onto…this is anywhere you have cloth beng layed down…outside that area you go to finer grit (150, 180, 220)…then you gloss…the finer grit on the perimeter makes the resin flatten out as there is less “tooth” for the resin to grab onto…it s much easier to blend thin brush strokes than it is a definitive line…plus less $ in tape. You can even us a new single edge razor blade for getting rid of the brush strokes (be careful doing this, keep it flat!) and eventually I started using the razorblade for the fine perimeter area before glossing instead of wasting time sanding that area with 220 or whatever.
By the way, this concept also works when you gloss a board and want to keep the weight down…we would sand the flats of the board (bottom and deck) with finer grits then leave the rails with 60 to 80 grit. This made for less burning thru the rails when polishing out the glosses
This is the difference between a pro that experiements and learns while in the trenches of board production and your average hobbyist.
You’re welcome.
Well…I have news for you. I developed a method for capping all my sailboard boxes (then ended up doing it on all the surfboard boxes as well) since 1980. I discovered the mesh of 4 oz can be applied right over the fin box cavity without taping.
Actally Thats exactly how I’ve been doing it. Except I use epoxy so it that makes it even easier to glass, just carefully brush the resin round the slot and swegee from the centre out if at all (if you brush on exactly the right amount of resin you only have to press the glass down very lightly) gives great resluts every time, saves time taping and cutting the glass is a breeze. I use a needle file in the corners of the lil slot.
What DS says is caorrect, I only give the cracks it quick wipe with styrene to see if I’ve sand enough, the cracks will reapear once the styrene evaporates but if they don’t completely disapare to start with then I know I’ve got to sand more.
I guess DS has done enough repars that he know exactly how much to sand out in the first place, but I like to double check. When your actualy doing the repair add the resin straight after the styrene just as DS say. sorry I my post was not as clear as DS’s
That tip on the gloss is excellent, makes perfect sence so I’m sure it will work, I will deffinately give that a try tomorrow.
Thanks for the great tip.
We want more!!
Hey Wouter…you know me from prevous threads…you have only cracked the surface of my forty years in the trenches…
DS
I’m going to do the 4 oz over the box right now
Thank you for sharing that with us
Tom
If you are not worried about looks, clear nail polish works. Same idea as the crazy glue.
Yeah, they’re all pretty much in the same ‘family’…Crazy Glue or Super Glue is an isocynate…like TDI and MDI blanks…plastics man!
DeadShaper, Great advice. There’s nothing like doing something over and over with the goal to make a living, to help you find the best and most efficient way to do something.
You just gave us some invaluable information. Thanks!
Doug
DS…thanks…you learn a lot over the years. Just the other day was telling some people how to sand glass and not get the itch. They were very appreciatve.
Aloha
yeah… you take a hot hot shower right before you start grinding shirtless!
NO!
You get a big container of cheap baby powder and sprinkle it liberally all over your arms esp. the inside part. The talc fills your pores and the glass fiber slides off the powder. When you finish sanding you use light glancing air sprays to blow the powder off your skin (not into your skin) and it all leaves in a cloud dust.
There are alos barrier creams that work pretty effectively.
No itch…don’t know about your hot shower theory.
umm… pretty sure the hot shower thing was a joke, eh? especially when followed by “shirtless grinding”…
hot water opens up the pores, cold water closes them. I always wash off any left over sanding dust with cold water, myself. For the same reason you’re filling up your pores with talc, there’s no reason to get them to open up, or they’ll fill with nasties…
obiwan either forgets there are real newbies here, or has a warped sense of how to teach others the hard (itchy) way what NOT to do.
KM…I was thinking some guy thought, take a real hot show and open up all his pores then goes out in the snow and sands his boards. He wonders why all his sticks come out with chatter after he glosses them.
When I was young I used to grinde the Radon boats in Santa Barbara, I didn’t know the baby powder trick til years later…the job almost killed me. One day Ronnie and Donnie and Les were laying up a boat and I was the mixer…I noticed someone had cleaned the cataylst dispenser which was unusaly but calibrated the catalyst and mixed as directed and brought the batch to the boat…Don looked at the resin and said, are you sure you catalyzed this, and I said yeah, 40 cc’s or whatever…turns out it didnt kick and they saved it with a later hot batch over it to kick the raw resin from that batch.
Someone had cleaned the bottle all right, then filled it with acetone! The next morning when I came in I found out what their detective work had disclosed. They relalized it wasn’t my fault but daddy Radon had a rule, and it there was a f-ckup, someone’s head had to roll. So it turned out to be mine.
It was the happiest day of my life! I hated grinding matt and roving all day until my ears rang and stinging in places I didn’t even know I had. I would have rather pumped septic tanks all day to be honest.
Live and learn.