There has been some discussion of penetrating epoxy used with wood skins. I believe it was Bert Burger who at one time suggested heat and pressure, or… solvents. Other than that, he was a bit vague.
A guy selling epoxy online demonstrates a formula of up to 25% acetone mixed with epoxy as a way to get it to soak in.
Similarly, I’m in the middle of a big wood varnish job and asked some boat people in the harbor about varnish and they said the same thing about 1st coat cutting 25% to 50% w/ mineral spirits for penetration. So, your mix for epoxy sounds right.
That’s a scary combo.
I thought this could be achieved with high pressure when prefabbing skins??? At least for the thickness of a compsand skin.
I thought mixing epoxy and acetone was wrong.
John, I can speak only for West Systems Epoxy as that is what I have used in my shop for over 30 years. First about solvent. Epoxy can be thinned withAcetone ,Toluene ,and MEK which would increase the penetration. But this is not recomended because it compromises the strenth and moisture resistance. This is how to do it without compromising your epoxy. And this is for bonding to wood. Example an wood surfboard. Yor heat the wood with a heat gun or heat lamp or by setting it out in the sun for a while on a warm sunny day . Then you mix your epoxy, best you use a slow hardener like West systems 206 . Apply with a brush to the warm (not hot)wood. Then heat the surface of the epoxy with a heat gun ,you can brush on more epoxy in the spots that look dry and heat some more with heat gun . When all the air Bubbles are gone you are finish with the heat gun. You could put it in a vacume bag at this point for more penetration but then do you want the extra weight of all that extra resin? Aftere the resin has gone off you could brush on more coats depending on what end results you are looking for. If you intended to do a clear coat finish without glass cloth you would do 3 coats of resin and two more coats of varnish brushed on or 4 coats of 2 part sprayed on. One more thing about solvents. I don’t recomend the use of acetone with epoxy as it can cause the epoxy to turn brown aftere some time. If you do use solvents for thinning the more you add the weaker and less moisture resistant your epoxy. To add 25% solvent is asking for trouble. Aloha Wood-Ogre
{edit} wood ogre beat me too it…
If you thin epoxy with acetone you will compromise it’s strength, furthermore you may trap acetone in the work and that could have all sorts of effects. Apart from acetone and epoxy being a magical recipe for skin allergy and acetone and amines being best kept away from each other, there is no real reason to penetrate deeply, if the wood is sealed with a coat of epoxy, it’s sealed that’s the main purpose. Any solvent will have to evaporate out of the gelling epoxy and leave microscopic “wake trails” as it moves to the surface, this will create a porous solid. Not good…
I would agree with west system and say if you really want a more penetrating and fluid epoxy heat is the way to go.
http://www.westsystem.com/webpages/userinfo/manual/index.htm#thinningepoxy
Penetrating epoxies are not meant for strength…
they are meant to penetrate with the hope of “sealing” or restoring rotted wood.
These techniques are as old as dirt.
Lots of folks using xylene.
LOL!
As boat builders would say…
Whatever floats your boat!!
Some testing done with this technique:
http://www.seqair.com/skunkworks/Glues/WestSystem/Thinning/Thinning.html
Some more great stuff on epoxy from the boat building world:
http://www.epoxyworks.com/indexprojects.html
Particularly this one:
Craftee,
Aren’t the super-thin formulations just for the prevention of outgassing and such on subsequent coats? I haven’t heard of it for rotting wood, but it seems like a good last-ditch effort. I am pretty sure they aren’t meant to keep out water, or be structural…
JSS
fosta,
Sort of off-topic, but I built a vacuum chamber that I use to dye wood all the way through. I pump the wood down for a few hours, then add the dye to above the level of the wood, and then put about 30 psi over the dye. You can see the dye level drop as the dye is being forced into the evacuated wood! Unfortunately, I am very limited on the size wood I can use (small size prototype), so I am building a larger one, to accomodate 6"x48" sheets of wood, and a little larger, so I can dye stringer materials, tailblocks, and hopefully pieces of an HWS (future project).
I wonder if something like it could be used to infuse epoxy. You could then almost ‘machine’ the wood. Things like making a Bahne finbox or any other normally plastic part could be done, if you don’t mind scraping the epoxy off of the insides of the vacuum chamber after infusion.
JSS
If you want a real good penetration, these folks make absolutely the best stuff
for sealing and “penetrating” wood.
I’ve seen it used to turn mushy wood that comes apart under your fingers
into stuff you can’t dent with a hammer.
http://www.smithandcompany.org
The real neat stuff they have glues teak,
purple heart, angelique, oak, better than anything I’ve seen.
I’ve seen it used in boat yards with more success than thinned
WEST or SYSTEM 3, would work really well for teak nose/tail blocks
Pete
Yo,
I hope that Greg Loehr will show up on this thread. He’ll have some very valuable info I’m sure,
Here’s my view on maximizing epoxy strength. Temperature and pressure are much more effective ways of maximizing epoxy bonding processes than fooling with the chemistry that has already been built into a given epoxy recipe. Epoxy recipes are varied and complex. Pick the one that comes recommended for the type of proceedures you plan on using. Beyond this make sure that you do you work in a controlled temp. environment. Start with the epoxy and work somewhere close to 75 degrees and have the temp. drop during the curing process. There is no substitute for the vacuum bagging process for maximum material contact and saturation. I’m no expert on vacuum baging the products coming forth in the surfboard industry using this process testify to it’s weight to strength ratio. If you aren’t goint to vacuum bag you need to have you material a optimum temperature and be sure to work out any so call holidays buy working pressure across your surface from the center out toward the sides and gradually pressing out all the air so no is trapped during the curing process. You’ll need a slow enough curing process to insure that you have time enought to work your composite material to have full penetration. Sometimes a roller is the best tool in your arsenal.
Come on down Greg!
No Worries, Rich
i wasnt gunna say anything
cant resist on this one
cant remember i think it was craftee that first suggested this (or the first time i read it suggested)
whats the point in using a lightweight/flexible, compressive resistant core.
if you are gunna make it stiff and heavy by adding resin
why not just use a slightlier heavier more water resistant wood
Exactly.
Not only that, but John was simply bringing up the topic of dilution to promote penetration and the discussion veered off into epoxy strength and property issues.
Isnt John simply talking about penetrating/sealing WOOD?
Is thinned epoxy supposed to strengthen pineWOOD?
Ok so balsa needs extra work and some sealing…
like Paul said, why not just use better stuff from the get go?
IMO, balsa is way over-rated.
or use it
and enjoy its properties for how they stand
and fix your pins and dings when they happen
hey john
ive used alcahol and xylene
with average sucess
its just the nature of balsa
it accepts water easily
but the epoxy has to be really thin to get any penetration
so thin that as wood ogre said its water resistance suffers
strength is irrelevant imo
vaccum works
but i cant just cant see the point
Hi Silly -
I don’t know… it (solvent) was something Bert threw out there. If he were still around, maybe he could answer although for some reason, he was rather secretive about the whole process.
Maybe do a search - “solvent” and check posts only by BertBurger?
Bert is/was a big fan of resin in the deck skin because it fortified the balsa making it better in compression (reducing heal impact damage). I’m not sure why he abandoned the solvent approach and went with his current approach (which also requires resin in the balsa but differently). Berts whole approach was to make the board so it was strong where it needed, but not where it was not.
the deck also highlights a common problem …
this is secret spice number 4 of which has never seen an appearance on sways …
unfortunatly to solve that one i had to spend some money on expensive equipment …
so the cheapest option , to solving it , is solvent related and knowing your timber if you dont want to spend the bucks …
regards
BERT
PS… if you do a search of Bert, use the spelling he used when he first registered - Bert_Burger, otherwise, you’ll get nothing.
Yeah Paul (Silly),
I remember hearing that said before, about just using heavier wood.
I have to say I don’t agree, no wood is ever going to be completely water resistant.
Discoloration sucks, as i’ve just found out!
So, the light weight of balsa gives you room to “preserve” it with epoxy, giving it true water resistance, and making it much harder than a heavier wood.
It should still come out lighter than something like cedar.
But, all of the approaches make a great board of course, depends what you want to achieve!
If your making them for yourself, and will look after them, may as well go light weight, save that extra 100grams!
I think Roy would be a great source of info on this thread, where are you TomBloke?
To those who havn’t heard about his work, Roy has done a helluva lot of wooden boardsin many configurations, with glass, just resin only, sealing oils, and about everything else you can imagine, from what i’ve heard! (Dunno if he’s tried groovy potions, snakes blood, and hemp oil, but I wouldn’t be suprised! … Just kidding ya mate 
he he)
Chime in man, give us the real story!
Kit