Fibre Saturation Point in Exotic Woods: Slab Drying & Epoxy

Understanding the Fibre Saturation Point in Exotic Slabs

In wood drying and tabletop construction, the fibre saturation point represents the threshold of moisture content below which wood starts to shrink. Above this moisture level, moisture resides inside the open cell cavities as free water. As free water evaporates during initial drying phases, the dimensions of the timber remain unchanged. However, once moisture content drops below the fibre saturation point, continued drying extracts bound water directly from the wood cell walls. This extraction of bound water initiates physical shrinkage along the tangential and radial grain planes.

For makers preparing custom epoxy river tables and live-edge slabs, understanding the fibre saturation point of exotic and imported lumber is essential. Technical data sheets published by CIRAD reveal that different timber species reach this shrinkage threshold at widely varying moisture levels. Pouring epoxy resin around wood that continues to lose bound water will cause the timber to shrink away from or pull against the cured resin, risking joinery failure, bond line separation, and surface distortion. Woodworkers should always consult the resin maker’s data sheet for general preparation guidelines while using botanical shrinkage data to gauge slab stability.

Exotic Species Ranked by Fibre Saturation Point

Data compiled by CIRAD reveals that the moisture content at which wood starts to shrink varies significantly across imported species. Wood species possessing a lower saturation threshold retain dimensional stability through a greater portion of water loss, while woods with elevated thresholds begin contracting much earlier during the drying cycle.

Low Fibre Saturation Point Species

The following timbers from the CIRAD records exhibit the lowest fibre saturation point figures, meaning they do not initiate dimensional shrinkage until moisture reaches comparatively lower levels:

• Macacauba: Fibre saturation point of 18 percent, with total tangential shrinkage of 4.9 percent.
• Moral: Fibre saturation point of 18 percent, with total tangential shrinkage of 6.1 percent.
• Afzelia: Fibre saturation point of 19 percent, with total tangential shrinkage of 4.4 percent.
• Cerejeira: Fibre saturation point of 19 percent, with total tangential shrinkage of 4.5 percent.
• Dina: Fibre saturation point of 19 percent, with total tangential shrinkage of 6.2 percent.
• Merawan: Fibre saturation point of 20 percent, with total tangential shrinkage of 6.6 percent.
• Preciosa: Fibre saturation point of 20 percent, with total tangential shrinkage of 7.5 percent.
• Tatajuba: Fibre saturation point of 20 percent, with total tangential shrinkage of 5.2 percent.
• African Padauk: Fibre saturation point of 21 percent, with total tangential shrinkage of 5.0 percent.

High Fibre Saturation Point Species

Conversely, these species exhibit exceptionally high fibre saturation points and begin cell wall contraction while holding substantial moisture:

• African canarium: Fibre saturation point of 40 percent, with total tangential shrinkage of 9.9 percent.
• East african bombax: Fibre saturation point of 38 percent, with total tangential shrinkage of 8.2 percent.
• Oboto: Fibre saturation point of 37 percent, with total tangential shrinkage of 9.5 percent.
• Angoa: Fibre saturation point of 36 percent, with total tangential shrinkage of 9.9 percent.
• Erimado: Fibre saturation point of 36 percent, with total tangential shrinkage of 4.8 percent.
• Essia: Fibre saturation point of 36 percent, with total tangential shrinkage of 9.2 percent.
• Ossimiale: Fibre saturation point of 36 percent, with total tangential shrinkage of 7.2 percent.
• Antiaris: Fibre saturation point of 35 percent, with total tangential shrinkage of 6.9 percent.
• Benguet pine: Fibre saturation point of 35 percent, with total tangential shrinkage of 8.9 percent.
• Mengkulang: Fibre saturation point of 35 percent, with total tangential shrinkage of 8.7 percent.
• Morototo: Fibre saturation point of 35 percent, with total tangential shrinkage of 9.8 percent.
• Pulai: Fibre saturation point of 35 percent, with total tangential shrinkage of 6.1 percent.

What Fibre Saturation Point Means for Drying and Epoxy Pours

When seasoning thick slabs for river tables, monitoring moisture content against the species-specific fibre saturation point prevents critical fabrication mistakes. For a species such as African canarium with a saturation point of 40 percent or East african bombax at 38 percent, the drying process involves an extensive range of active shrinkage. A slab cut from such timber must undergo substantial bound-water loss, accompanied by steady dimensional movement, before reaching equilibrium.

In contrast, woods such as Afzelia at 19 percent or Macacauba at 18 percent lose significant volume of free water before entering the shrinkage zone. However, an epoxy pour should never take place while wood moisture remains near or above the fibre saturation point. Encapsulating wood with unevaporated water traps moisture, interferes with proper adhesion, and risks severe wood movement once the finished piece enters interior living conditions. Checking slab moisture content across the entire thickness confirms that the timber has fully moved past its fibre saturation point and stabilized prior to pouring resin.

Species Data Reference

The complete CIRAD dataset below outlines fibre saturation points alongside total tangential shrinkage percentages for exotic and imported timbers:

Wood	Fibre saturation point (%)	Total tangential shrinkage (%)
Macacauba	18	4.9
Moral	18	6.1
Afzelia	19	4.4
Cerejeira	19	4.5
Dina	19	6.2
Merawan	20	6.6
Preciosa	20	7.5
Tatajuba	20	5.2
African Padauk	21	5.0
Difou	21	5.7
Idéwa	21	7.0
Manchiche	21	6.2
Muirapiranga / Bloodwood	21	5.9
Pucté	21	8.9
Rosewood Para	21	8.2
Vêne	21	5.9
Yellowheart	21	6.5
Cumaru / Tonka	22	7.7
Freijo	22	6.3
Garapa	22	7.5
Gheombi	22	6.8
Guariuba	22	6.5
Pau mulato	22	8.2
Resak	22	4.7
Tamarindo (Groçai-rosa)	22	6.4
Wacapou	22	6.5
Wenge	22	9.1
Angelim amargoso	23	7.8
Angelim vermelho	23	8.5
Angelin	23	7.3
Ayan	23	5.8
Cabreuva	23	8.0
Coconut wood	23	6.1
Congotali	23	10.8
Coula	23	8.5
Iroko	23	5.4
Louro branco	23	7.1
Mecrussé	23	6.2
Moabi	23	8.7
Suren	23	6.3
Timborana	23	6.9
Wamara	23	8.3
Yellow balau	23	9.5
Abiurana vermelha	24	9.1
Baracara	24	8.1
Catucaém / louro faia	24	12.3
Guanacaste	24	4.5
Iatandza	24	4.9
Jequitiba	24	5.3
Keranji	24	6.6
Macucu de paca	24	7.6
Mambode	24	5.4
Merbau	24	4.4
Merpauh	24	7.2
Niove	24	6.0
Ovangkol	24	8.0
Pau marfim	24	8.6
Rubberwood	24	5.6
Angelim pedra	25	8.3
Bilinga / Opepe	25	7.5
Black wattle	25	7.0
European Cherry	25	8.4
Ekoune	25	6.9
Eveuss	25	9.5
Grenadillo / Grenadille d’Afrique	25	4.8
Izombe	25	7.0
Mango (Machang)	25	6.1
Manniballi	25	9.5
Melunak	25	8.3
Mubala	25	9.9
Musizi	25	4.9
Nieuk	25	6.4
Okan	25	7.9
Ossoko	25	6.5
Pterygota	25	9.6
Rengas	25	5.3
Tanimbuca	25	9.2
Amesclào	26	8.6
Ananta	26	9.2
Araracanga	26	9.8
Batibatra	26	9.0
Brazil nut	26	10.0
Brown sterculia	26	10.0
Capomo	26	7.0
Copaiba	26	5.9
Cupiuba	26	8.8
Diania	26	7.4
Djedoe	26	8.2
Etimoe	26	7.5
European Larch	26	8.2
Gerutu	26	8.0
Gombé rouge	26	7.4
Gombé towé	26	7.9
Black Guarea (Bossé Foncé)	26	7.0
Kanda brun	26	6.0
Kapokier	26	5.4
Kedondong	26	6.5
Kembang semangkok	26	7.9
Manilkara	26	10.1
Mora	26	10.0
Mukulungu	26	8.4
Mumuli	26	8.3
Owui	26	8.1
Pashaco / paricá	26	5.5
Pyinma	26	6.8
Sepetir	26	7.5
Tali / Missanda	26	8.4
Yemane	26	5.9
African walnut	27	5.8
Agba	27	5.4
Beli	27	8.9
Dabema	27	8.5
Dakama	27	8.2
Douka	27	6.9
Ekop	27	7.8
Idigbo	27	5.2
Itauba	27	9.7
Magas	27	6.7
Massaranduba	27	9.4
Mutenye	27	8.8
Pakuri	27	10.0
Red balau	27	8.8
Sandbox	27	4.7
Senegal mahogany	27	5.6
Simpoh	27	7.6
European Walnut	27	7.5
Wamba	27	9.5
Alep	28	10.9
Andok	28	11.2
Andoung	28	7.4
Ariella	28	6.0
Berlinia	28	7.8
Canon ball	28	6.6
Cardeiro / Cedrinho	28	10.0
Atlas Cedar	28	6.0
Cow tree	28	8.2
Cryptomeria	28	6.9
Ekki	28	10.3
Radiata Pine (European Plantation)	28	7.4
Eyoum	28	8.7
Goiabao	28	11.6
Mountain Pine (Hooked Pine)	28	8.3
Jacareuba	28	8.1
Kumbi	28	6.6
Kurokai	28	10.0
Limbali	28	9.1
Makoré	28	7.5
Mansonia	28	7.4
Odoko	28	9.3
Ohia	28	8.4
Ossabel	28	7.7
Sapucaia	28	9.8
Sesendok	28	4.3
Snakewood	28	10.5
Tauari	28	7.0
Tchitola	28	7.5
Vésámbata	28	9.5
White seraya	28	8.5
Abarco	29	6.6
Alumbi	29	7.9
Basralocus	29	8.2
Cedrorana	29	6.9
Faveira	29	7.0
European Silver Fir	29	8.7
Gommier	29	8.0
Igaganga	29	7.8
Kanda rose	29	8.0
Louro vermelho	29	8.8
Manil / Manni	29	10.1
Maporokon	29	6.9
Nyatoh	29	7.7
Olène	29	10.1
Piquia	29	8.2
Piquiarana	29	9.6
Tasmanian oak	29	10.0
Uchy	29	10.6
Wallaba	29	6.5
Angueuk	30	11.8
Bodioa	30	10.3
Cedrinho	30	9.3
European Sweet Chestnut	30	6.9
Curupixa	30	7.9
Danta	30	7.5
Kasai	30	10.0
Kauri	30	5.9
Keledang	30	5.5
Landa	30	8.8
Lati	30	10.8
Melancieira	30	10.7
Ogea	30	6.8
Okwen	30	6.8
Olon	30	5.7
Perupok	30	5.9
European Poplar	30	8.3
Punah	30	9.2
Safukala	30	7.9
Scots Pine	30	8.3
Utile	30	6.4
Zebrano	30	11.0
African cordia	31	4.6
Aningeria	31	7.0
Bintangor	31	7.7
Dukali / amapa	31	7.7
Geronggang	31	7.7
Scented Guarea (Bossé Clair)	31	6.8
Longui	31	8.2
Mandioqueira	31	9.7
European Oak	31	9.7
Onzabili	31	6.9
Ozouga	31	9.1
Patula pine	31	8.3
Pyinkado	31	6.7
Quaruba	31	9.8
Red grandis	31	10.0
Abura	32	8.9
Alstonia	32	5.2
European Ash	32	9.6
European Beech	32	11.6
Gedu nohor	32	8.0
Jacaranda	32	8.5
Kosipo	32	6.7
Maritime Pine	32	9.0
Marupa	32	6.3
Merkus pine	32	8.0
Mersawa	32	8.8
Niangon	32	8.8
Ceylon Satinwood	32	8.3
Anzèm / nténé	33	7.0
Ilomba	33	8.6
Kelat	33	8.7
Ovoga	33	7.3
Ozigo	33	7.3
European Spruce	33	8.2
Ceiba	34	6.3
Dalli	34	9.5
Keruing	34	10.0
Osanga	34	5.8
Sougué	34	10.1
Sterculia	34	10.1
Sumauma	34	6.3
White sterculia	34	10.6
Antiaris	35	6.9
Benguet pine	35	8.9
Mengkulang	35	8.7
Morototo	35	9.8
Pulai	35	6.1
Angoa	36	9.9
Erimado	36	4.8
Essia	36	9.2
Ossimiale	36	7.2
Oboto	37	9.5
East african bombax	38	8.2
African canarium	40	9.9

Data compiled by BigEpoxy from individual CIRAD Tropix 7 technical sheets (average values for mature wood).

Sources

• CIRAD Tropix 7 technical sheets (index)

Published October 31, 2026. Sources are linked in the text.

Header image: original graphic by BigEpoxy.com.