heres something interesting
http://www.gore.com/en_xx/products/venting/technical/outdoor_electronic.html
aussie distributors
+64 2 9473 6800
im sure they know what the windsurfer dudes use
Have you tried using veil cloth to prevent the pinholing, would add a bit of weight, but maybe not if you can get away without hotcoating? I recently got hold of some to do some tests with but I’m waiting to get my vac kit all set up before I start mixing any more resin up.
No I havn’t tried it!
Never seen any actually…
I just googled it, didn’t come up with much information.
Sounds like its very fine fibre cloth, but i’m not sure what it is about it that will give a pin-hole free finish?
Whats your understanding of how it’s supposed to work?
Or how you plan on using it?
I’m interested…
Doesn’t sound like it will add much weight.
The extra weight is actually a secondary concern for me, it’s the large amount of time and labour that hotcoating adds that is my main reason for trying different to find a solution.
I’d love to hear more about it, cheers man!
Kit
From what I’ve read it seems to be fine fibred tissue matting, used as an outer layer on a lamination. I was reading some of the old posts from MrJ on here, and he mentioned that the rc aircraft modellers were way ahead of surfboard builders when it comes to composites. So I headed over to the rcgroups.com forums and had a bit of a dig around.
There were a few people over there having pinhole problems, and the photos that they posted showed exactly the same problems that I’d been having. Bit more digging and the possble solution seems to be to firstly degas the resin, paint the wetout table as mentioned above and lay the veil cloth down and let the resin saturate the cloth from below (ideally the veil cloth and woven fibreglass at once I suppose, but not sure if that will give problems when draping over the board), adding extra epoxy from above and spreading with a grooved roller if required, then placing the laminate on the board, with the side that was down on the wetout table now facing up and hopefully air free at the surface. I guess if you were just doing the rails and using a silicone sheet you could lay the stack straight onto that and then flip it onto the rails.
So that’s going to be my next experiment, I’ve got a piece of foam painted black to show up any voids/pinholes, but I’m still waiting to get some more resin before I try it. Here are the pages I bookmarked when I was looking into it:
http://www.rcgroups.com/forums/showthread.php?t=269370&pp=15
http://www.rcgroups.com/forums/showthread.php?t=294033
http://www.rcgroups.com/forums/showthread.php?t=349497
http://www.rcgroups.com/forums/showthread.php?t=544239&page=3&pp=15
http://www.rcgroups.com/forums/showthread.php?t=527653
http://www.rcgroups.com/forums/showthread.php?t=461394
Mark
I tried to post to help you with your problems but the dam spell checker tossed my post. So my apologies I’m a bit late to this.
There are a few different things that you can try to help your rail wrap. Both will make for an easier way to secure the cloth to the rail before bagging, but to have a sand free bottom and rail that is the holy grail. If you could use a resin that stays in a liquid state for 2-3 hours you might be able to pull it off. Either that or glass in a walk in freezer. Let me know if you can figure that one out because sanding is the worst.
First out lay your glass out on a table, put your board bottom side down on the glass, and use a circle cutter to cut the glass to a wider shape of the board. If you’re the anal type you can even use a guide so that the glass is perfectly the same all the way around. If you’re smart you can also cut the glass for the deck and bottom all at once. Use the cut glass as a template for every thing else, breather, release, veil, etc. The veil or perforated release should be and inch or two wider than the cloth.
Glass or wet out your cloth either on your board (easier) or off the board (harder). If you go with the .58 oz. veil it is incredibly resistant to unraveling and acts like super fine silk when wet out. In fact unless you’re cutting on a marble slab the circle cutter will not cut the veil. Think of wrapping your board with a very strong and fine spider web. Just be careful when you lay it out that you try to lay it out flat on the first try onto the wet out glass.
Make sure that you’ve got all the air out of all the glass; apply the perforated release, and then your breather. Now comes the part that will make you cringe. You can either flip the board over onto the breather bottom side down on the layout table (easier) or try it on the stands (harder) you staple the breather and perforated release right onto the board. Yes it will dent and yes it will make holes but you will never know when you’re all done. As you’re stapling you are pulling and flattening out the perforated release and breather. I use very few staples and no you won’t be able to get it all perfect, but with practice you can get very close.
Just make sure that the glass doesn’t get over your release or breather. Stick it in the bag and crush it flat with vacuum. If you are using a good bagging material you can smooth the whole thing out at 1/4 vacuum before you apply the full pull.
Any small creases are flattened and I can get away with very little sanding just to prep the board before you do the deck.
There are little tricks to help. If I’m using perforated release I always go full vacuum 21 hg’s. The perforated release controls saturation of the cloth, in fact you can do different variations on your lay-up to control how dry your glass will end up. Peel ply under the perf. release, no breather over the perf. release, lower vacuum, heating the board before the resin kicks to make it less viscous, etc. You need to use scrap bits of whatever type of foam you’re going to use and try different combinations to see what works best for your resin type, lay-up schedule, temperature, etc. etc.
If you want more tips on all this type of stuff go to the Yahoo Groups Boardbuilding. This is where all the techno vacuum baggers hang out. One of the members figured out a way to do a perfect non sanded finish right out of the bag, but he isn’t sharing, only teasing with pictures and obscure tips.
Quote:
From what I’ve read it seems to be fine fibred tissue matting, used as an outer layer on a lamination. I was reading some of the old posts from MrJ on here, and he mentioned that the rc aircraft modellers were way ahead of surfboard builders when it comes to composites. So I headed over to the rcgroups.com forums and had a bit of a dig around.
There were a few people over there having pinhole problems, and the photos that they posted showed exactly the same problems that I’d been having. Bit more digging and the possble solution seems to be to firstly degas the resin, paint the wetout table as mentioned above and lay the veil cloth down and let the resin saturate the cloth from below (ideally the veil cloth and woven fibreglass at once I suppose, but not sure if that will give problems when draping over the board), adding extra epoxy from above and spreading with a grooved roller if required, then placing the laminate on the board, with the side that was down on the wetout table now facing up and hopefully air free at the surface. I guess if you were just doing the rails and using a silicone sheet you could lay the stack straight onto that and then flip it onto the rails.
So that’s going to be my next experiment, I’ve got a piece of foam painted black to show up any voids/pinholes, but I’m still waiting to get some more resin before I try it. Here are the pages I bookmarked when I was looking into it:
http://www.rcgroups.com/forums/showthread.php?t=269370&pp=15
http://www.rcgroups.com/forums/showthread.php?t=294033
http://www.rcgroups.com/forums/showthread.php?t=349497
http://www.rcgroups.com/forums/showthread.php?t=544239&page=3&pp=15
http://www.rcgroups.com/forums/showthread.php?t=527653
http://www.rcgroups.com/forums/showthread.php?t=461394
Mark You have to be carefull with the veil. It’s not an end all to the pin hole problem. If you do a carefull wet out on the board air shouldn’t be a problem. I stopped using it because I found just by reducing my vacuum and fully saturating the cloth that I could get away from the veil. Veil also can be tricky. If you have some cut out a small patch and saturate it with resin to play with it. Also I would never put it down first I doubt that it would come off the wet out table. I would put it on last after the cloth is fully saturated on the board. Once on and flat it sticks like glue and almost vanishes with no need for additional resin.
Thanks for the tip, I’ll take care when I start playing around with the stuff I’ve got. Does anyone use the unidirectional cloths that you know of? Seems like they should give better mechanical properties in theory, and with fewer spaces in the weave might help with the pinholes too. I guess the cost might be prohibitive.
If you go to http://www.acp-composites.com/acp-mats.htm you will find a selection of materials that can be used with excellent results.
You should try to figure out why you are getting pin holes in the first place and then adjust from there. It might be as simple as doing a quick seal of your substrate first or turning your vacuum down. Another trick is to do your wet out and then let the epoxy kick to a more viscous state prior to the vacuum.
I even know of a major board builder that doesn’t even use vacuum. He just glasses, applies a thicker mil plastic, wets the outside of the plastic with water and squeegees all the air and excess resin out of the cloth, pulls the plastic tight and lets it kick. No wasted fancy bagging materials, no need for a pump and best of all you can see everything through the plastic. The theory is similar to applying window tint to a car. I even heard of a guy that swore that shower curtains worked the best for this type of technique.
The plastic and squeegee method is what I had been using, just on hotcoats to save sanding at first, and then a few tests straight over the glass. I could squeegee out all the air bubbles, but then more would form, minimising bubbles in the mixed resin helped, as did dropping the temperature after laying the plastic on, but still a long way from zero pinholes. Very nice apart from the pinholes though, used little resin and the thicker plastic helped to fair out any imperfections and lap ridges. I’m hoping to get one of the joewoodworker polyu bags and try a similar technique under vac straight over a wet lam, I expect a lot of trial and error to get a combination of materials and technique that work, but for me that’s better than the time and hazards of a lot of sanding.
i dunno guys
Sabs showed me a 6 4 the other day that was 4 pounds
i dont think he used vacuum to do the outer glass
if it doesnt kill the pinholes, theres really no point
the easiest way to kill pinholes is to seal the balsa/blank first
and fill the joints between the sheets, as thats where the pins usually form
it doesnt take long to sand a board
In Tom Sullivan’s instructional video he showed how he put a thin poly sheet over his hand lamination, smoothed it all out, taped the underside to add tension and popped little holes in the plastic to let air escape before bagging.
Apparently some folks don’t bother with vacuuming over the plastic sheet. He stated he prefers the finish using the sheet within a bag.
He also stresses at this point to make sure the temperature is dropping in the room to prevent outgassing.
This is the best thread in a while!
This site has been mentioned before, http://www.kiteboardbuilder.com/130LaminatingTop/. He has pictures of many of the ideas floating around in this thread, including wrapping the peelply around the rails.
I like the idea of painting the resin onto the plastic first. In fact, my foam supplier told me that’s how we was doing his work, he called it “poor man’s infusion”.
From my experiments, the thicker the bag, the finer the finish.
My 30mil bag makes a surface like glass, my 4mil nylon bag creates an orangepeel surface. You guys all reuse your bags right?
Intriguing is the word to describe the idea of not completely glassing the rails. If we can live with that bad spot where the bag and rail separate, then we’re in fat city. Sand off the burr, hotcoat it, blend it, done!
What if the board was placed into the bag perpindicular, on its edge? In a way that the bag conformed around the rails and the bag seams were located on the bottom and deck?
Burt always said there was no need for release film and breather cloth, was this a trick? I don’t think so. With careful application of the resin in the first place, there really isn’t any excess resin that needs special handling.
Bumping
- this thread is really good–
and
- in case KKsurf has pics of the folding method he uses to do wet-out, and question about multiple layers being wet-out at the same time using this method, assuming epoxy and slow-cure
Not sure if someone has answered this already but here it is again if they have.
[url]http://www.swaylocks.com/forum/gforum.cgi?post=183391;search_string=sandwich%20construction;#183391
[/url]
For fun and giggles, I did some small fg/epoxy test panels this week.
One was 66 open weave surfboard cloth, the other was tight weave 3333.
Each stack started at 8.8 grams dry (lucky).
Poured the epoxy on and spread with a squeegee, then further pulled extra resin off the cloth. The 66 finished at 14.1g, the 3333 13.2 grams.
Thats better than 1:1 using a simple hand tool.
They both had similar flexural props, the 66 being slightly stiffer, but the 3333 was 0.016" thick vs 0.020" for the 66. However, the surface finish was miles apart. The 3333 had a much finer finish over the 66. The 66 would require much more fill coating and sanding. Theoretically, you could fine 220 grit sand the 3333 after a very light brush coat. Point being, you can have very good ratios without complex wetout methods.
Yeah, but what did you wet it out on?
EPS bein’ thisty an all.
do you think finishing a normally glassed board with an extra layer of glass at say 2 oz would do the same thing in terms of reducing the amount of fill coat needed and the sanding needed? I’ve noticed that when I glass with 4 oz on the outside I get a much better finish.
Yes, that is likely the case.