Enough glass? How long before I have to sand again?

Homerr

Commander
Joined
Mar 4, 2002
Messages
2,294
I'm doing the 4" and 6" strips of glass on each side of my stringers.<br />I would like to follow up with a final piece overlapping the 4/6 up to the top of the stringer leaving the top flat so the floor will sit right.<br />I also put in some cross-pieces between the stringers where the floor sections meet (at 4' intervals)<br /><br />I'm working with 2 stringers, 1@ 10" x 19ft, and 1@ 6" x 17ft.<br /><br />I'm using 17/08 biaxial.<br /><br />The engine block/bilge area is fully wrapped with glass as factory did.<br />Factory didn't run glass all the way up the entire stringer or use cross pieces between.<br /><br />I know I went over-kill on the first side of the boat and probably used way too much glass. You could drive a tank up on that side of the floor and it wouldn't budge!<br /><br />I'm running low on materials, and I hope I can get by with what I have.<br /><br />It's hard to think that a small amount of glass can be so strong. I keep thinking a 26ft. boat needs a lot of strength, when it fact it probably doesn't. Based on the old stringers i removed, a couple of tooth picks would have been better!<br /><br />Also, I coated both stringers Sunday evening, and did the 4/6 on the inner stringer. Last night I wrapped the engine area.<br />How much time do you think I have before I need to sand or scuff the resin on the other stringer?<br />It's been cool here (around 50).<br />The glass I did do has already set up quite nicely.<br /><br />I thought I read somewhere that as long as I'm using layup resin (which I am - Us Composites)<br />that I don't need to scuff the resin before applying new glass. <br />I know it's best to do it all at once, but working for the man all week cuts into my project time!<br /><br />Thanks!<br /><br />H.
 

crab bait

Captain
Joined
Feb 5, 2002
Messages
3,831
Re: Enough glass? How long before I have to sand again?

sounds like your givin' it he77 ,HOMER..!!<br /><br />you don't need the extra (3rd ) piece of biaxial at all.. it's a waste an serves no perpose... <br /><br />the cross braces is a good move.. beef it up intellegently,, an without alotta extra weight ..is a good thing..just remember to 'mousehole' them first as so for drainage..<br /><br />i'd scuff/sand it anyway.. <br /><br />an can be scuffed as soon as 'kick-off'..the sooner the better cause its scuffs easy... <br /><br />get H E A V Y sandpaper.. deep cut is better for adhesion.. if'n you use a drill motor/disk.. i love only GREEN 3m disks.. they're about 60 grit.. an last forever..if gets clogged,, should always have a big 'eraser' .. made for it uncloggin' sandpaper an cheap cost..well worth it..<br /><br />HOMER,,like i said before.. its all one tied together unit.. <br /><br />the floor ties it all together... do a good job there...
 

CCrew

Chief Petty Officer
Joined
Sep 10, 2003
Messages
416
Re: Enough glass? How long before I have to sand again?

You technically need to sand again after the epoxy has set.. . If you're using the 635 Thin layup epoxy with medium hardener (3:1) from US Composites, that's for sure. The bond will not be as good between layers if you don't, as it does blush. I've done destructive tests on some scraps, makes a BIG difference in bond between sanding and not. If it's past 8 hours, I wait 24, sand, and acetone before laying more glass on existing. <br /><br />If you want a good test, resin coat 2 pieces of wood, let them dry 24 hours. Sand 1, not the other, lay a layer of Biax on them, let them dry. You'll be able to separate the biax from the non sanded board... If you take a power sander to it, you'll see that you can't feather edge the unsanded board, as the edge rolls up at the first coat/glass layer. That convinced me..<br /><br />-Roger
 

snapperbait

Vice Admiral
Joined
Aug 20, 2002
Messages
5,754
Re: Enough glass? How long before I have to sand again?

If it polyester laminating resin without a surfacing agent, and if the surface still feels tackey, I would'nt sand.. Just go over everything real good with acetone or styrene on a rag...
 

BillP

Captain
Joined
Aug 10, 2002
Messages
3,290
Re: Enough glass? How long before I have to sand again?

If it is polyester laminating resin it should be too tacky to sand. Laminating res will stay tacky for months. If you want to prep it again wipe the surface with styrene...and no sanding is required. Styrene provides a chemical bond...superior to the tenacious bond provided by sanding.
 
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