I’m really glad that you were able to try it out so soon - and that it actually worked!
Hey Dan,
Nice looking boards. I didn’t realize that this is how you were doing it. We would never do it this way in the composite world unless using prepregs. The problem with the glass against the formica, is what you and everyone has caught on to — the air gets trapped by the resin and has no where to go. You lucked out with the thin balsa being porous enough to allow the trapped air through it, and also pull any excess resin into it.
FYI, the other way to do it, which will work with non-porous cores, is to use this schedule: formica, balsa, glass, perforated release film, breather/bleeder. You’d be surprised how good the finish comes out this way. It’s not quite ready to go, because of the bumps caused by the perforations, but pretty good after some light sanding. Also, this way provides the best control over glass to resin content.
I’m really looking forward to your findings on how the boards contrast.
if your laying glass on a smooth caul plate (formica), squeeging all the excess, laying balsa on top of that, another layer of low resin glass on top, why bag it? if you use pressure w/o vac the finish on caul side will be mirror smooth…hmm, yeah vac baggin does make adding pressure easier.
btw kenz, having a textured surface on the inside isnt such a bad idea…as you proly know 
combined with a mirror smooth outside surface…yeah good stuff
I wish i had some spare time to make another balsacompsand…i rode my flexible one yesterday and its defintely got tail flex…i rode a long wave towards the beach purposely carving it hard and it was denifitely flexing…ive got another one similar to it that way stiff in comparison…been measureing board flex too in the ‘lab’…my lastest bcs (i really should name them…like Betsy) had the highest score…cool, im glad im not imagining things
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if your laying glass on a smooth caul plate (formica), squeeging all the excess, laying balsa on top of that, another layer of low resin glass on top, why bag it?
If you glass both sides, how do you attach it to the blank and with what?
regards,
Håvard
hey H,
lots of options there…
one way is to attach it the normal way…as if you would if the inglass wasnt there…
and if theres concern over deck curvature, then that can be premolded/shaped as well…
plenty of solutions out there.
prefabbed skins has its benefits and imo, the biggest one is mfg efficiency…like when working with pre-p’s…sooo much potential there.
some would argue there are other bennies too…i would agree just to different degrees and priority
guys are so freaked out over Sunova’s style performance potential, but i you saw how he makes’m you’d be really freaked out…
…notice how little he talks about production…it really sets him apart…kudos to Bert
and by the way H,
I know you know a lot, and im learning every day. but wrt to this stuff ive learned more looking outside of surfboards…
why would a 60 y/o lady buy a $400 graphite tennis racket?
because she wants to.
why wont surfers buy $1000 surfboards?
because theyre cheap.
and thus, the common hi-perf surfboard is stuck in the 20th century.
there’s soo much cool composite shit out in the sports world…there’s more tech in snowshoes then there is in surfboards…boards are laggin 10-20 years…
freakin snowshoes man!!
its truly remarkable!
things are changing and black monday might just be the spark
if theres concern over deck curvature, then that can be premolded/shaped as well…
Hi Meecrafty -
Dan says he gets the skins to conform to those complex deck curves at 5" vacuum. He’s using a specific grain orientation in his balsa pattern but it still sounds like the skins are fairly flexible.
I wonder if using higher temperatures, higher vacuum or perhaps different impregnation resin, an even stronger skin could be prefabbed?
The hardwood flooring, musical instrument and duck call people are using some sort of acrylate solution - METHYL METHACRYLATE. Under vacuum it can penetrate wood structure and basically turn it to plastic.
I think it’s similar to bone cement (PMM) used in orthopedic surgery. Here is a cut/paste on bone cement from an orthopedic site… The familiar materials Plexiglas or Lucite are pure polymethylmetacrylate.
A prefab skin impregnated with something like that might have to be molded to fit deck curvature as you suggest.
Here’s something else from a musical instrument (recorder) site… They also mention Lucite/plexiglass. If they can impregnate an 8" square billet of exotic hardwood, a thin sheet of balsa should be a piece of cake.
ALTERNATIVE IMPREGNATION STRATEGIES
Just when plastic recorders are making their products look like wood, there is interest in making wood/plastic composites. Sometimes the goal is cost, sometimes fashion, and sometimes it is the elusive immortal woodwind. The technique is not new. Amish farmers have impregnated maple wheel bearings for over a century with lard. The WWII Maytag ringer-washers used mineral wax impregnated maple. Most techniques today are aimed at the floor panel, knife handle, and designer pen body market. But woodwind makers may possibly realize shape stabilization, and water repellency. Only time will tell.
METHYL METHACRYLATE (MMA): Wood Stabilizing Specialists Inc. (Cedar Falls, IA), has produced a billet of cherry impregnated with polymerized methyl methacrylate. Scott Hirsch, a flute maker in Coleville, WA, has made instruments from the material. Wildwoods (Monclova, OH) has produced similar impregnated billets of maple and black-dyed birch for Powell Flutes (Waltham, MA). Tim Bernett of Powell Flute made an impregnated maple alto in the mid '80s. Bamboo has been treated for use in making Japanese flutes; Yamaha has worked with impregnated rosewood for clarinets. Roger Rowell of the USDA Forest Product Laboratory has explored impregnating maple wood with MMA for recorder manufacture.
The pure polymer is the well known Lucite or Plexiglass. Such impregnated woods do pose challenges to the craftsman because of brittleness, the need to use low turning speeds and coolant because of the low melting point of the plastic, and a tendency to clog sanding materials. Finished instruments play well and seem to have good dimensional stability. Some results are reported in Woodwind Quarterly, #2, August 1993. Such impregnations for many commercial purposes began in the 1960’s. Ken Caines of WSSI reports load factors of about 50% are normal with common woods. Exotics, such as ebony, accept much less polymer (<10%) and are prone to bleed displaced “wood oils” for many months after treatment. This can be removed by wiping with acetone. Odors from the monomer are often prominent, and are due to excessive water in the impregnated wood (>10%), or improper curing. Drying (40 C) can remove such odors.
OTHER ACRYLATES: Many other efforts in wood impregnation exist. Daniel Deitch, a Baroque woodwind maker in San Francisco, has utilized cyanoacrylate impregnation for wood stabilization. MMA has the structure H2C=C(CH3)COOCH3, while a typical cyanoacrylate has a structure H2C=C(CN)COOCH3. They differ by the substitution of a -CN group for a -CH3. This substitution makes it easier for the material to polymerize into long carbon chains, much like a zipper closes. The cyanoacrylates are used as rapid setting “glues”. Deitch swabs out the finished bores with the cyanoacrylates, lets the material polymerize, and then finishes the interior surface. Deitch also reports that he has been pleased with a technique for finishing the exterior learned from Rod Cameron, a flutemaker from Mendocino, CA. A few drops of the cyanoacrylate are added to linseed oil, and the mixture applied as a hardening finish to the exterior. The cyanoacrylate accelerates the hardening of the mixture. Do not be concerned about the presence of the -CN group in the molecule. It is an organic nitrile or cyanide, not an inorganic cyanide. The latter are toxic, but the organic -CN is not. Some artisans find the cyanoacrylic bore finish beads water excessively.
OTHER FORMS OF POLYMERIZATION: The polymerization of both the cyanoacrylates and methacrylates depend upon chemical induced free radical formation to begin the polymerization. A free radical is a carbon with only three groups around it, and one lone electron. This poses some interesting problems in getting complete penetration into all the void space of the porous wood. The cyanoacrylates react with air and polymerize quite rapidly, providing good near surface penetration. Free radical initiators added to the methacrylates allow somewhat deeper penetration before blockage occurs. Firms such as Applied Radiant Energy (Lynchburg, VA) have developed an alternate strategy for achieving an even more complete penetration. The methyl methacrylate is forced into the wood by first applying a vacuum, then flooding the chamber with the liquid acrylate, and finally bringing the head space up to atmospheric pressure. They can achieve loadings of 10-100% in this way, filling a great deal of the void space. The polymerization of the material is then induced by exposure to gamma radiation. This ionizing radiation penetrates the wood completely and evenly, allowing uniform polymer hardening throughout. The degree of polymerization can be carefully controlled by the amount of irradiation. This permits careful adjustment of the working properties of the resulting composite. Don’t be concerned about the radiation initiator. Gamma radiation is just like an X-Ray beam. Once the beam is turned off, its gone. The route has been used to sterilize food for long term preservation. Gamma radiation DOES NOT consist of radioactive particles which have long half-lives, and which slowly emit hazardous particles and radiation.
Billets up to 8"x8" have been treated. Ash, oak, pine and poplar are common. More exotic woods include cherry, ebony, and jatoba (Brazilian cherry). Best results come from using the heart wood. Robert Turner, a Charlottesville, VA recorder maker, is experimenting with some of the materials.
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btw kenz, having a textured surface on the inside isnt such a bad idea...as you proly know ;)combined with a mirror smooth outside surface…yeah good stuff
That’s right! I use a teflon coated fiberglass porous release fabric called Armalon. It leaves a nice textured bondable surface. The standard nylon release fabric works well also, but I like the Armalon because it’s reusable.
So yeah, one could do both sides at once in a bag with a schedule like this: breather/bleeder, porous release fabric, glass, balsa, glass, perforated release film, breather/bleeder.
And with all the talk about infusing the balsa with resin, this might be the perfect application for vacuum resin infusion. For this you have to use a lower viscosity resin, so it will most likely fully saturate 1/16" thick balsa. At the next Cerritos function we should see how much penetration we get using this method. So if anyone wants to try it, the schedule for vacuum infusing is pretty similar, you just replace the breather/bleeder layers with flow medium. By the way, Greg has an epoxy for infusion.
Also, I was thinking of the best way to attach the skins to the blank, and wanted to get some opinions. Since the additional adhesive would add weight, what about apply the adhesive in a grid pattern instead of covering the entire surface. For example, I was thinking of using a 1" grid pattern, using a bead of polyurethane glue. Do you think this would compromise strucural integrity compared to full coverage?
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And with all the talk about infusing the balsa with resin
I’ve been thinking about making a few test panels using infusion. I’m think that infusion in boardbuilding requires a different path than what people are thinking. Its much more out of the box. The main thing thats holding me back is the cost of the resin traps - what a ripoff!
They are a good idea, but you don’t really need a resin trap. Just use a lot of extra tubing for your out port, and keep an eye on it. When you see full saturation, clamp off the input port immediately. We never let the resin get to the resin trap anyway — too messy. And tubing is cheap.
Maybe you could make a resin trap out of PVC pipe. Just glue it together and make a new one when it (if it ever) gets full.
I don’t completely understand the point of pre-making the skins. I bag on a skin with both inside & outside glass at once and get the same result. Not only do I save a step in & out of the bag, but I don’t need extra resin/adhesive to stick the skin to the foam.
Measure out the resin & hardener & glass, lay out the balsa, tape it together. Wet out glass #1 (inner) and roll it out on the balsa. Flip the blank down on that, flip the whole works back over. Peel tape, wet out second sheet of glass, roll it out on the balsa (outer). Add peel ply, paper towels, and a stripe of shade cloth…everything goes into the bag neat & tidy.
1/16" balsa either gets fully saturated or stays dry, depending on what I’m shooting for, by how much resin I add to the INNER glass. All excess resin from the outer glass comes out through the peel ply & gets picked up by the paper towels. One hit, no extra resin.
I guess if you had a laborer & wanted him to make you 100 skins & set them aside, that would be one reason to do it. Or if you could stack them up with layers of release film in between and make a dozen at a time in one bag. But otherwise, I don’t get it. Am I missing something? Am I not getting the same result?
I was going to give it a try this way, but at the last minute went back to the preformed skins. I can’t tell from you picture, but does your skins turn out so that you don’t need to hotcoat it. Thats my end goal (I’m very close to it). Like a lot of things I think which technique you use comes down to personal preference. The preformed skins will work better with a direction that I want to go in the future (I’'ve got a few crazy ideas running through my mind). However, I do think that the higher pressure offers some advantages for getting resin into the wood.
Dan,
Yeah, resin trap prices are a MASSIVE ripoff, since you can make one out of an old jar and some blutack.
Your pantry is full of resin traps!
Hi Dan - no, I fill coat. But if I put smooth plastic over the outer glass instead of the peel ply & absorbent, I wouldn’t have to. That’s what I gathered from Bert’s comments about almost looking finished right out of the bag. Even more resin would be pushed into the balsa that way, too.
I was going for light & dry on that one, so I was looking for minimum resin/maximum control. It worked 
What is Bluetack?
Blue sticky stuff I use it for all my final vac seals… Including sealing my bag. Real cheap stuff too.
Try Blutack.com.
Some piccies to give ya the idea…
They do other colours now, too.
Dan
I have sucessfully made cheap resin traps from 4" pvc pipe (Guttering down pipe) with the ends made from 1" ply epoxied onto the ends.
The inlet and outlet pipes are standard pvc plumbing fittings epoxied into the wood on one end.
Cheap and just bin them if and when they fill up.
Better to be safe than sorry and get resin into your pump.
Thanks, I’m now pretty much settled on going the pvc trap way. I’ve never made a test panel, but I think to get infusion wired I’m going to need to make more than a few.
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I don’t completely understand the point of pre-making the skins. [snip]Am I missing something? Am I not getting the same result?
I would think you could use higher pressure which in turn could meen less resin needed. You could also bag it in an autoclave that would both crush and melt the EPS. To me it sound easier to do the prelaminated balsa as you do less things in one step which meens less things to screw up. Plus you don’t need the throwaway peelply.
A hundred ways to skin a cat I guess.
regards,
Håvard
That is for sure, it is expensive, that peel ply.
no extras, but epoxy penetrated balsa.
Only problem is how to get the best bond to the foam wiht pre’fabbed skins,
anyone feels like updating?
Wouter