I have had a problem recently with my rails.
I do a single 6 oz bottom and a double 6 oz deck.
I overlap the rails with all three coats.
I then hot coat, sand smooth, and then gloss coat.
I always expose the cloth when I sand the rails even when I sand by hand with high grit.
Any advise on how to prevent the problem, I was thinking of doing a second and maybe third coat after the gloss coat before sanding, but thats a lot of extra weigh and work.
Thanks for any input.
Hey NY,
I found that the best way to have a good sanding experience is to do a good hotcoat. I have a few questions for you:
You say you overlap the rail with all three layers of glass. How much overlap do you have on the inner layer of deck glass? Does it go all the way to the bottom side? If so, you are making things harder for yourself sanding-wise. Check out page 128 in the 1977 Surfboard Design and Construction book (I don’t know of a current link for it, but search Sway’s and you should find a good link if you don’t have it).
It is very difficult not to expose weave on the bottom near the rails, because you are trying to make everything even and ‘level’ (depending on bottom contours), and you have a 6 oz ‘shelf’ sitting there where the lap ends. Is this where you mainly see weave? If so, the gloss/seal coat will take care of this weave.
How do you hotcoat and gloss? You’ll find that with epoxy, viscosity and speed are the things that count most. You control viscosity with heat, AddF and DNA, and your hands control speed. What you ideally want is a resin mix that will flow easily, but start to get very hard to brush well as soon as you are done ‘walking’ or ‘tipping’ out. With epoxy, different temps will change things quickly (like if you do this in a garage). You want to do the second side of a hot or gloss coat on a falling temp, so you don’t have any little bubbling volcanoes of resin from the blank outgassing. A way to guarantee this is to heat up the blank in a hotbox (one of the ‘to-do’ things on my list to build), before you coat. As for speed, you want to do it quickly, but with no frothing (viscosity helps with this).
I have a system that works great for me now, but it only works at 75 degrees F. I now do everything in a garage, so I’ll have to chnge things up a bit to account for the increase in temp.
Also, if you have pictures, it would help me figure out what you are doing…
JSS
The main reason I’m asking is I used to have these problems, and I used to do 2 hotcoats per board…sometimes 2 glosscoats per board.
Are you sanding thru the weave or just exposing the weave beyond the hotcoat?
I’ve found that making the rails absolutely perfect before the hotcoat helps me quite a bit. I sand the rails before the hotcoat if there are any lumps or bumps, then hotcoat, then sand again. For me, every successive layer of glass compounds any flaw from the layer before so I ensure each one is perfect before the next one goes on. Its slow but it works for me, epoxy is a pain in my ass but what you gonna do?.. I have to do three or four at once to make it worth the time.
Hope it helps.
Howzit ny,Try basting the rails before hotcoating. This fills in the weave and adds a little buffer zone to help prevent sand throughs. Aloha,Kokua
Hi NY -
Exposed weave is different from a sandthrough.
Ideally you wouldn’t hit the weave when sanding but I think most people do. I’ve noticed at least some weave exposed on literally EVERY sanded board I’ve ever seen… some worse than others. I’ve also seen sandthroughs (all the way through the weave) on brand name boards that were merely covered with gloss resin.
I think some guys are using a single layer of light cloth over the main laminate as a sacrificial sanding barrier. As Kokua mentions, a baste coat along the overlaps before the hotcoat helps too.
Unless those spots are really thin or all the way through, in which case you might want to do a little “ding repair”, just do a finish coat over the sanded hot coat. There are some guys who have the skill and results to survive a rigorous qualty control inspection. As hobbyists, most of us aren’t going to be working for Moonlight or Cooperfish.
Will post some pics on monday night, thanks for the replys.
I am not going all the way through the way, just exposing it.
But when 95% of the board looks good those areas that show any weave at all
just drive me crazy.
I do a single 6 oz bottom and a double 6 oz deck.
I overlap the rails with all three coats.
I’m not a Pro…
When lamminating the deck only one layer needs to over lap. This might solve some of the sand throughs.
With RR epoxy I’m working with only 6 oz cloth…
EPS / EPOXY is different …not better or worse. Temp is super important
Do the lam , hot coat ,sand everything , hand sand the rails and then lay down a clean coat of resin. Some call it a second hot coat…
I’m not a pro, but I used to do the same thing everytime. now i just take a utility knife blade and scrape the rails then just hand sand with 220. works well for me but can be time consuming, esp if the hotcoat isn’t very even.
kokua’s technique works, used it on my first . . . also use the razor to take that bead on the edge down . . . as others have said . . .
I found out if I used hard sanding blocks on the rail or use the sander on the rail it’ll expose weave quick. I just use hands and soft flexible packing foam for taking down the rails.
Also it helps to mainly use long motions and follow through whole rail as opposed to spot sanding . . .
Also for areas with the weave, just touch up the area . . .
Howzit hiroprotagonist, Nice to hear my technique works for you. If you want to use a grinder for the rails try a soft Ferro pad, they are so soft they don't sand through unless you over sand. One technique I use when hand sanding is to sand the rails like a shaper does,wrapping the paper around the rail and running from nose to tail.Aloha,Kokua
One more thing to try, get rid of that 6 oz. I only use it on the longboards. For any other board we’re doing double/triple 4 oz. over 1.5# EPS. The lighter cloth makes such a huge difference in the finish. Plus, the boards are stronger and actually lighter. I do a double lap with the bottom layers, then a butterfly patch to just above the front foot with full double over that, only lap with the top layer. Really happy with this lam schedule, costs just a little more in cloth, but uses no extra resin. Also really helps to paint the rails, all logos, and the patch line as stated above. Buttery sand outs… That 6 oz weave is just too much to fill with the super thin epoxy hot coats in my opinion.
Problem is that I have like 100 yards of the 6oz, I am going to try the basting of the rails before the hotcoat.
Will post pics when board is done, I am doing an inlay on wed. and then will glass over the weekend.
Kokua’s lap “basting” has been standard for me for years. It provides a smooth transition for the sharp edge where the cloth ends, and also fills any voids/pin holes on the laps. On poly boards, I do the basting with sand resin, sand it down (die grinder w/2" disks), and go over it again with a thinned lamcoat. The same can be done using RR epoxy.
Exposed weave happens because of the vertical surface of the rails which flows off more hotcoat than flat surfaces. There are very few people who can do such a perfect lam and hotcoat that needs such minimal sanding to not expose weave on a vertical surface. A thinned-down glosscoat over a smooth and level sanding of any hotcoat can start sanding with 320 or higher (another Kokua tip). Polish it or leave it at 800. I use thinned-down poly gloss over RR epoxy hotcoats sanded at 80. Less sanding/higher grit = less exposed weave.