how to select rough balsa for your own blank

Ive been trying to find some rough balsa to start building my own balsa blank but i have know idea what to look for.? grain,color, there seem to be different weights light is 6 to 10lbs per foot med is 10 to 14 lbs per sq foot and heavy is 14-19 .which one would work best? as for the stringer which way does the grain need to go? can i use something a little different from redwood or balsa for the stringers? any help would be really helpful.



I like 4" x 8" x 10’ timbers.

11 pounders are nice but hard to find.

Balance your board by the weight of the balsa.

When you block sand be careful of the difference in soft and hard wood.

Plan your glue up accordingly.

Watch out for spalted wood as it will disolve as you shape it.


Western Cedar looks really good against the color of the Balsa.

Plus your bay will smell awesome while shaping it out.

If you are going to surf it you need to chamber it.

I take considerable time to make them from complete scratch.

However it is pretty rewarding once you finish one.

thanks for the reply "Watch out for spalted wood as it will disolve as you shape it. " what is spalted wood? and when im planing my glue up where do i want the lightest and softest wood would i put the heavest wood in the center maybe?



Spalted wood is the result of the start of the decay process. It will appear as dark (black) streaks. Sort of an abstract pattern. You see it a lot in balsa boards. If caught in time, before it gets too punky, it can add to the overall design. Just be careful if you use it that its not too soft.

Look for wood that is really light in color with a pinkish tint to it, that is the lightest stuff.

I think you want to distribute the heavy wood equally across the board; either in the center or on the rails so the board balances. Remember, you can chamber more weight out of wood in the center of the board than on the rails. The denser wood should be more difficult to dent, so using it on the rails can be a plus.

If you can keep the wood in a dry climate (not that possible in Wilmington) you might want to kiln dry it first (if it wasn’t purchased that way) then bag it up between shaping sessions to minimize exposure to humidity.

Either own or have friends who own stuff like joiners and thickness planers. It is wood ya know…

Shaping and glassing a balsa were the most rewarding experiences I’ve had in making surfboards.

Spalting is any form of wood coloration caused by fungi. Although primarily found in dead trees, it can also occur under stressed tree conditions or even in living trees. There are four distinct types of spalting, however only three of them are actually considered pleasing.

[/url] Types

Spalting is divided into three main types: pigmentation, white rot and zone lines. Spalted wood may exhibit one or all of these types in varying degrees.

[/url] Pigmentation

Also known as sapstain, or in its most common form, bluestain, this type of spalting occurs when the darkly-pigmented fungal hyphae grow in the sapwood parenchyma of a tree [1][2]. A visible color change can be seen if enough hyphae are concentrated in an area [3]. These pigmentation fungi often colonize wood via the rays, but are not considered decay fungi due to their non-destructive use of easily available wood carbohydrates [4][5]. The most common groups of pigmentation fungi are the imperfect fungi and the Ascomycetes [5]. Mold fungi, such as Trichoderma spp., are not considered to be spalting fungi, as their hyphae do not colonize the wood internally.

While pigmentation fungi do not degrade the wood cell wall, this type of decay can lead to a reduction in toughness (amount of energy absorbed before breaking), and increased permeability [6]. Pigmentation can occur on both hardwood and softwood, unlike other types of spalting which are more host specific.

[/url] White Rot

The mottled white pockets and bleaching effect seen in spalted wood is due to white rot fungi. Primarily found on hardwoods, these fungi ‘bleach’ by consuming lignin, which is the slightly pigmented area of a wood cell wall [7]. Some white rotting can also be caused by an effect similar to pigmentation, in which the white hyphae of a fungus, such as Trametes versicolor (Fr.) Pil., is so concentrated in an area that a visual effect is created [8].

Both strength and weight loss occur with white rot decay, causing the ‘punky’ area often referred to by woodworkers. Brown rots, the ‘unpleasing’ type of spalting, effect these same properties, but at a much faster rate [3]. Both types of rot, if left uncontrolled, will turn wood useless.

[/url] Zone Lines

Dark dotting, winding lines and thin streaks of red, brown and black are known as zone lines. This type of spalting does not occur due to any specific type of fungus, but is instead an interaction zone in which different fungi have erected barriers to protect their resources [5]. The lines are often clumps of hard, dark mycelium, referred to as pseudosclerotial plate formation [9].

Zone lines themselves do not damage the wood, however the fungi responsible for creating them often do.

[/url] Conditions

Conditions required for spalting are the same as the conditions required for fungal growth: fixed nitrogen, micronutrients, water, warm temperatures and oxygen [10][3].


Wood must be saturated to a 20% moisture content or higher for fungal colonization to occur. However wood placed underwater lacks sufficient oxygen, and colonization cannot occur [6].


The majority of fungi prefer warm temperatures between 10 and 40°C [6], with rapid growth occurring between 20 and 32°C. [11]


Fungi do not require much oxygen, but conditions such as waterlogging will inhibit growth [12] [13].


Different fungi require different amounts of time to colonize wood. Research conducted on some common spalting fungi found that Trametes versicolor, when paired with Bjerkandera adusta, took 8 weeks to spalt 1.5" cubes of Acer saccharum.[14] Colonization continued to progress after this time period, but the structural integrity of the wood was compromised. The same study also found that Polyporus brumalis, when paired with Trametes versicolor, required 10 weeks to spalt the same size cubes.

[/url] Commonly Spalted Woods

The Ohio DNR found that pale hardwoods had the best ability to spalt [15]. Some common trees in this category include maple (Acer spp.), birch (Betula spp.) and beech (Fagus spp.).

[/url] Common Spalting Fungi

One of the more tricky aspects to spalting is that some fungi cannot colonize wood alone; they require other fungi to have gone before them to create more favorable conditions. Fungi progress in waves of primary and secondary colonizers [2], where primary colonizers initially capture and control resources, change the pH of the wood and its structure, and then must defend against secondary colonizers that then have the ability to colonize the substrate [2] [16].

Ceratocystis spp. (Ascomycetes) contains the most common blue stain fungi [17]. Trametes versicolor, (Basidiomycetes) is found all over the world and is a quick and efficient white rot of hardwoods [2]. Xylaria polymorpha (Pers. ex Mer.) Grev. (Ascomycetes) has been known to bleach wood, but is unique in that it is one of the few fungi that will erect zone lines without any antagonism from other fungi [18].

[/url] Spalting Research

Initial lab work was conducted on spalting in the 1980s at Brigham Young University. A method for improving machinability in spalted wood using methyl methacrylate was developed in 1982 [19], and several white rot fungi responsible for zone line formation were identified in 1987 [20]. Current research at Michigan Technological University has identified specific time periods at which certain spalting fungi will interact, and how long it takes for said fungi to render the wood useless [14]. Researchers from this university also developed a test for evaluating the machinability of spalted wood using a universal test machine[21].