Drying Balsa

[CharlieN]

I am getting ready to make some car parts utilizing Balsa core and this brings me to a question I have not seen addressed here.
Are you guys drying your Balsa before laying it up? The Balsa draws in moisture during storage and can benefit from being dried out before encapsulating it in a layup.

[OFFSHORE GINGER]

Are you Kidding ........................................ and just curious where are you keeping your core considering you are so concerend about moisture during storage before layup ........lol , and with out trying to be rude, i think it is all about common sense unless you are keeping it out side or in the shower .........Ha Ha Ha

[XstreamVking]

If you are concerned about some core possibly being wet, just put some in a plastic bag and then put it in the sun. If it makes a sauna in the bag you have problems.

[olboatman]

I am not kidding here--- ANY wood I encapsulate weather for boats or building construction I put in a room that is tight (next to my shop) and turn up the heat and a dehumidifer. If its going to a restoration job (old building) I transport it in sealed plastic sheating. Its amazing how much more epoxy or presertive it will absorb especially if you treat it as it cools down. Sounds like a lot of work BUT I was tought to do the best job I can and charge accordingly. Gary

[CharlieN]

I generally do dry it in the sun, in a black plastic garbage bag with a partial vacuum drawn on it. And no I am not kidding, being the balsa is all end grain it takes very little time to draw in an appreciable amount of water especially if a storm has passed by recently.

But for those that still use Polyester resin there is no need to bother with this, the balsa will be wet again soon enough.

[OFFSHORE GINGER]

Well with all that in mind post # 4 sounds like a lot of X-tra work , and to tell you the truth it is .............because if you are doing a very large boat or repair most likely you will never get the core fully Encapsulated in one setting after it has been installled or laid down , and to tell you the truth i have seen core sit ( opened ) at just about every Boat Co that i have ever worked at with no problem's .......

[CharlieN]

and to tell you the truth i have seen core sit ( opened ) at just about every Boat Co that i have ever worked at with no problem's .......

And how many boats need to be recored?
Personally if the core is dried or not has little to do with it rotting in the future. How it is installed and what resin is used is a major part of what determines the life of the hull.
I do not know of many boat companies that can spend the time to dry the wood going in, Heck enough of them never sealed the drain tubes when they were being swaged in place.

Drying the balsa does have an effect on the adhesion of the resin but also makes a difference to the final weight of the product. For most people doing an open wet layup that will not matter anyways.

Bagging the core, even if left exposed, you can draw a vacuum before closing out, if time allows.

[olboatman]

But for those that still use Polyester resin there is no need to bother with this, the balsa will be wet again soon enough.[/QUOTE]

Well said! Gary

[XstreamVking]

Then how do you explain the 30 year old poly/balsa/plywood built boats with no rot? Done properly I assure you poly, or vinylester is more than adequate for sealing balsa core.......I built a boat for a friend over 30 yrs ago that I am around a lot, and it has no rot or cracks in the hull. 17' with a 200 hp merc. It was built with poly resin and wood stringers, balsa for core. I have re built many old poly and wood boats over the years and some were in real good shape with no rot after 30+ years. Epoxy is good stuff, but will not stop rot if sloppy construction is used. Don't blame the material for sloppy workmanship.

[dagodiver]

Then how do you explain the 30 year old poly/balsa/plywood built boats with no rot? Done properly I assure you poly, or vinylester is more than adequate for sealing balsa core.......I built a boat for a friend over 30 yrs ago that I am around a lot, and it has no rot or cracks in the hull. 17' with a 200 hp merc. It was built with poly resin and wood stringers, balsa for core. I have re built many old poly and wood boats over the years and some were in real good shape with no rot after 30+ years. Epoxy is good stuff, but will not stop rot if sloppy construction is used. Don't blame the material for sloppy workmanship.

What he said.!!


Dago

[CharlieN]

Any boat stored well will age well.
Polyester resin is hygroscopic, always has been, always will be. Poly resin for the most part does not adhere to wood.
Shrinkage rates between 2 to 7%. Poly is brittle, get worse with age.

Vinylester pretty much is waterproof, still has a moderate shrinkage rate. It also adheres to wood fairly well.
Vinylester is a great replacement for poly resins.

Epoxy only absorbs moisture during its cure, Then is waterproof. very low shrinkage rate.
Adheres to wood very well. Pretty good tolerance to flex depending of formulation.

Then what few boater will have worked with are the Urethane resins, these are now becoming popular. Sticks tenaciously, superb water resistance, flexible with good impact resistance.

Personally I have not worked with poly resin in more than 20 years, I just see no value in staying with a 80 year old resin system with the advances we have available to us.

[XstreamVking]

Only two reasons why they still sell poly. It's lower price. And it works well for a lot of applications. And as for proper storage being the difference, my buds old poly boat is either in the water or hanging several feet above it. Only type of cover is for the console. Really, I don't know a worse way to store a boat. But, still no rot or cracks. Real world outcomes sometimes do not reflect scientific type findings.

[CharlieN]

More than likely the durability of that boat is a testament to the work you performed and not to the materials used.

[RobF]

the resin has no bearing on the balsa rotting out, that is just a silly statement.
we, and i KNOW ginger- have recored PLENTY of epoxy/balsa boats with wet core- the water came from the INSIDE not even through a hole or damage.

You see 30+ year old poly/balsa core boats without core issue it fails from the end user putting unsealed holes not from the resin.

Further- to say poly doesnt stick to wood is also not accurate at all- cut the back of a perfectly dry transom off or skin a dry balsa construction layup and let me know how easy it is to get that wood off the fiberglass.


Good luck with your car parts project- keep your balsa core in the house where its air conditioned or next to a dehumidifier for a couple weeks before you start its not like it smells bad

[OFFSHORE GINGER]

Charlie , lets face it............... most boats that need to be re-cored are due to poor work men ship or a lack of , and not to mention that i have worked at more then a few high end Boat Co's over the years that use Epoxy in there build with no problems concering moisture in the core before fully encapsulating it , and in the past or should i say years i have seen many boats ( core that is applied ) sit in the mold for weeks , months , sometimes a full year that are not fully encapsulated depending on the build or if the boat has a perspective buyer in line .