My idea is to make a finbox out of balsa and vacuum this juice into the wood to get a kind of hard resin wood finbox. since it replaces the air within the wood, the balsa should become very hard, like epoxy(?) and therefore it could be an ideal method to create own finboxes, leash cups etc., especially in wooden boards.
By now I just sealed the wood for my leash cups from the outside , but herewith you would create an artificial wood from the inside.
Also, aren’t there different types of strength depending on the vector(s) through which force is applied? Like compression strength, flexion strength, torsional strength…and resin only will increase one or some of those perhaps?
Since it should replace a standard plastic fin box, or a plastic leash cup, I do not really care about the weight, my intention is to get a nice “wood” looking finbox, which I can make relatively easily by myself and which lasts.
I’ve read, that the more porous the material is, the better are the results, so, since I use balsa anyway for most of my boards, why not use balsa scrap for finboxes.
Remember, foam surfboard strength comes from the glass and not the resin. The resin gives some compression strength though not lot. The glass is what keeps the board from snapping.
Come on guys! This is Swaylocks! Remember? Something out of nothing? Why buy something you can make? In the “Spirit of Sways”. Etc. Personally, If I wanted the all wood look, I would just set the box a hair below surface and veneer over it. That would give you a strong box with the high impact plastic channel for the fin and the veneer would give it the “wood” look. But that is just too logical and this is after all “Swaylocks”.
Yes… and No: The resin keeps the glas strands from moving, especially in its woven form and so does the resin with the balsa fibres. If the glas was just fixed in front and tail of a board it would snap, because it would work like a spring (what it does anyway, but on a much smaler scale; thats the reason too, why twill has better mechanical properties like canvass.
I think (like your concern) the mechanical stresses of fin boxes are more pressure than shear or lengthwise orientated, (See your first post) and I expect the resins weak point are puntual pressures (so your concerns are obviously right)
But I hope, that the pressure resistance would be enough; thats why I asked whether anybody had worked with this stuff and can share some experiences. Stabilized Wood is used by knifemakers a lot for handles, because it makes especially porous wood (some already moulded partially ones too) durable.
But the weak spot is between the veneer and the box. If the epoxy does not bond well to the box, and if the veneers edge is not sealed properly, or the sealing damaged, it ruins the veneer very fast…
It’s difficult to completely saturate wood, you need vacuum and pressure cycle in an autoclave.
A good product for deep wood protection is water base epoxy. You can thin with water to a realy fluid that cured far less porous than high VOC resin. Those water resin became a standard for wood boat build. I use Resoltech 1010.
i use to saturated thin wood sandwich skin, first from vacuum clamping process with resin rich fiber under and drain over then i use fluid water base resin over. No more water wood intake. I flexural strengh.
Thanks for this! I did not know anything about waterbased epoxy, very interesting.
I think the charm of the acrylic resin lies in the fact that you can reuse leftovers as long as they have not been heated.
Put the resin and dry wood in some kind of exsiccator, wait appropriate time, take saturated wood out, store the rest of the resin, heat the wood, done…
I think another candidate for your job is clear vacuum infusion epoxy resin. The stuff is pricey, but I keep some around for small void filling jobs. I presume it’ll soak into wood easily. I may be using it for its intended purpose soon, and that’ll be a glass over wood job. I’ll do a test setup first before I actually work on the part. So in a month or few I may have some information.
One part acrylic resin i ever see stay on the “soft” plastic range. Water based epoxy come from the “no voc” laws, you can clean tools with water no solvent use, i think first application was for industrial ground paint.
You can autoclave small wood parts in a wood cooker with a heat reactive resin : put wood in a cooker and make vacuum then inject resin over part from an other point (like infusion), stop vacuum and add pressure, wait a moment, put part in an oven to harden resin. I never do it but see a vid of guy that make knife handle like this.
i use température variation to increase capillarity phenomen : let wood cured in oven around 40 to 60°C. Pull out oven and as wood temp fall soak with fluid imprégnation resin up to full saturation.
This is very interesting too, it should work with low viscosity resin (if part fits well into container, not much epoxy will be left over, which may be easier and cheaper; this could be combined with vaccuum but it will be difficult, because of the leftovers, unless you use the waterbased epoxy) With the heat working acrylic resin it would not work very good, because if the part is hot, the resin starts immediately, prior to intruding into the pores, to harden…
… unless the time to set even if hot is long enough… A variation could be heating up the wood, drying it to a low humidity percentage, and then immediately your temperature variation method. If it takes for example 20 min for the resin to set, this combined with your method will allow enough resin to intrude prior to start heat setting. It could be left in the vac for some time (it will cool dwon within minutes anyway, but after some hours you can cook it to set the resin completely. This may be a way to achieve good results. I think I will go and try it, but first I would need a plexiglas tube to make an exsiccator for a 2,5x2,5x30mm piece of wood. A half meter tube with 30mm inside diameter would be perfect, you could build even longer than usual fin boxes, which gives more variations for positioning the fin…
Seeing the knife makers use this method, brought me to the idea…
Thank you very much in advance for sharing the experiences. The problems I see with epoxy is, that the epoxy have to be activated by mixing hardener and resin. Even if you manage to get your object fully saturated out of the vaccuum, the leftover epoxy in the chamber will harden or has to be removed, but cannot be used anymore. So you need for example 40gr to saturate wood, but 500ml to bathe the wood in. 460ml are spoiled and ruined undless your object fits perfect into to “bathing container”. The acrylic resin allows to separate the saturation, vaccuum, pressure procedure from the sole hardening by heating.
Yes, glassed over. By now it works flawlessly, but I’m afraid to hurt the veneers edge directly at the rim of the box. While changing or adjusting the fin, I’m very careful to avoid evrything possible, but the last edge is only chamfered and sealed. If this gets a damage the wood might be open and suck water, but it is as possible that the veneer is mostly saturated with resin and even if damaged nothing will happen. If I would veneer an upcoming board anyway, I would insert a plastic box, but If no veneer is the plan, a stabilized wooden fin box, if the stuff works, would be perfect.
I saw one technique where they put the wood onto a banking sheet and into an oven to heat it up, mixed their resin up so it would be ready when the wood came out of the oven and immediately brushed it in. The idea being the cells would draw the resin in as it cooled. I actually tried it myself with thin piece of aircraft ply but it already had glue in between layers so I didn’t get any penetration past the outer layer.
Veneer is thin, though. You should be able to seal that. Make a plate to cap your finbox, glass it on using non-woven veil to get some adhesion between the box and plate, and then cap the plate.
I like using a slow very thin and warmed resin like System 3 clear coat resin for initial saturation of warmed wood, but this specific epoxy formulation is rather old now, and not cheap either.
When one adds denatured alcohol or Xylene to epoxy to thin it out, I do not trust that the mechanical properties of the epoxy have not been compromised, nor subsequent secondary bonding efficacy.
I have no issues using mineral spirits to thin polyurethane for the initial sealing coat of wood in non surfboard related woodworking, but thinning of epoxy other than by temperature, scares me.
I don’t believe epoxy bonds as well to the Fin box material as PE resin does no mater the amount of mechanical tooth and acetone wiping of it. I’ve had glass lift off near the slot all too easily, and would not trust it with a Veneer adhered right to the edge.
I use wood stabilised with vacuum infused resin on occasion with my knifemaking work. Some of those are cactus juice infused. It makes the wood seriously solid and dense. I like the term plasticised wood - I think it will work!
