Sanding Firewire boards

[Jackson]

Just been patching some spider cracks with a layer of cloth/epoxy and I was wondering what grade of sandpaper would best match the finish of Firewire boards?

Cheers

[iggy]

Well I use the green part of the sponge for washing dishes as a finisher

[prjwebb]

I tend to use anything upwards of 400 grit wet sanded. Cooker (Firewire's San Diego repair guy) suggested 320 to me followed by Dolphin skin polish.

The finish sanding is always the same: sand the shape down
lightly with 150, and 220 then 320 to get the scratches out. The polish
we use called "Dolphin skin" but not really necessary, once it gets wet
it will look good.

I've never used the polish, but have always been happy with wet sanded 400 grit finishes.

[Jackson]

cool, good to know. thanks

[Chris]

good stuff prj. yeah the sponge trick is good.

[Jackson]

Well I seem to have made a dogs dinner out of what should have been a simple spider crack repair.

I just can't get the resin to adhere properly and it peels and flakes away when I start sanding the repair. It's the first epoxy repair that I've tried and it's getting the better of me.

Here's what I did/used:
- cleaned the damaged area with a surfboard de-waxing product and used a hair dryer to evaporate any residue.
- using 60 grit paper I sanded around the spider cracked area on the rail to the point where I could see the weave of the cloth.
- removed dust making sure I didn't get any oil from my hands onto the sanded areas.
- masked the area with tape.
- applied Phix Doctor epoxy sun cure resin with a new/clean brush and saturated a patch of 4oz cloth with plenty of resin.
- curved a sheet of plastic around the repair to fit the shape of the rail making sure there were no air bubbles.
- exposed the repair to direct sunlight for a few minutes.
- carefully removed the plastic and tape
- exposed the repair to direct sunlight for another 10 mins.
- start sanding the repair with around 200 grit paper.

At this point, the new glass just starts to peel and flake all the way to the edges of the cloth patch. I can then get a finger nail under the edge of the cloth and pretty much peel it off. I've repeated this process (except de-waxer) 3 times now and every time I have to sand more of the board away.

I've decided to take it to a pro ding repairer, but can anyone tell me what I'm doing wrong? Just pretty concerned about what I'll do if I get a ding when I'm away in Indo.

Thanks

[iggy]

let it cure for a bit longer!!!. That happens usually when:
1)Your resin vs catalyzer proportions are not right
2)You don't give enough time to cure

[prjwebb]

Epoxy is very different to poly. It definitely needs that extra time to harden or it does just fluff and peel as you sand. Sounds like you're going about it right though.

I'd buy some 2 part epoxy and forget about the sun cure stuff myself. Weigh out both parts to get the quantities right and give it a full 24 hours to harden.

My first couple of repairs where with a ding all epoxy kit and I found that resin flaked a lot when sanding. It was impossible to feather out the repair properly. I've since got some epoxy from a local blank blower/shaper supplier place and had much better results with that. It doesn't yellow quickly like the ding all stuff did either!

[Chris]

Also make sure you sand into the ding a bit. Not a ton, but enough to that the level of the rail is taken down a fraction. then glass and let set. then sand to shape and match the rail.

remember, if you put glass on top and then try to get your rail to match the rail around it, you'll blow through the repair every time.....

Hope this helps