Wood Treatability Classes: Liquid Penetration and Slab Prep Guide

Understanding Heartwood Treatability for Table Slabs

When selecting timber slabs for custom wood and resin tabletops, understanding how species receive liquids is essential. Wood treatability classifications documented by CIRAD evaluate how easily liquids—such as wood preservatives, liquid stabilizers, or thin seal coats—penetrate into the heartwood structure. For a tabletop builder, treatability indicates whether an applied liquid will absorb deeply through cellular pathways or remain restricted to the outer wood fibers.

In porous, permeable timbers, liquid seal coats and penetrating treatments move inward freely. This deep intake helps secure the foundation, but it can also pull liquid away from the surface quickly, demanding extra attention to seal off air pathways before a primary pour. Conversely, timbers classified as not permeable resist liquid movement completely. Understanding these distinctions allows builders to tailor shop preparation to the specific physical behavior of each species.

Heartwood Treatability Groupings

CIRAD classifies heartwood permeability into distinct ratings, ranging from easily permeable to completely non-permeable. Below is an overview of these groupings and how they behave when liquids are applied to table slabs.

Class 1: Easily Permeable Heartwood

• Representative Species: Alstonia, Aningeria, Antiaris, Bodioa, Canon ball, Capomo, Ceiba, Cow tree, Diania, East african bombax, Ekoune, Erimado, European Beech, Geronggang, Guanacaste, Ilomba, Jacaranda, Jelutong, Kapokier, Kembang semangkok, and Kumbi. (Dalli is rated Class 1-2, moderately to easily permeable).
• Liquid Behavior: Heartwood in this class absorbs liquids readily. Thin seal coats, low-viscosity stabilizing solutions, and liquid preservatives travel deep into the cellular structure with minimal resistance.
• Shop Considerations: Because these woods drink liquids rapidly, a single thin surface application will often sink entirely beneath the surface, leaving dry areas. Applying multiple thin seal coats helps saturate the open internal network and stops trapped air from releasing later into tabletop flood layers.

Class 2: Moderately Permeable Heartwood

• Representative Species: Abura, African Padauk, Andoung, Angelim pedra, Baracara, Benguet pine, Bilinga / Opepe, Cedrinho, Cerejeira, Cupiuba, Curupixa, Dakama, Dukali / amapa, Durian, Ekop, European Ash, Faveira, Gheombi, Goiabao, Kauri, Longui, and Magas. (Cedrorana, Coconut wood, and European Silver Fir are rated Class 2-3; Cryptomeria is rated Class 2(v)-3(v) with variable behavior).
• Liquid Behavior: Capillary uptake occurs at a steady, moderate pace. Liquids penetrate into outer layers without immediately draining completely away from the boundary line.
• Shop Considerations: These timbers provide balanced absorption. Sealing steps require standard monitoring to confirm that edge pores are thoroughly wetted and stable prior to downstream casting steps.

Class 3: Poorly Permeable Heartwood

• Representative Species: Abarco, African cordia, Agba, Alep, Amesclào, Angelin, Angoa, Angueuk, Araracanga, Ariella, Atlas Cedar, Batibatra, Beli, Berlinia, Black wattle, Brazil nut, Brown sterculia, Cardeiro / Cedrinho, Copaiba, Coula, Dabema, Difou, Dina, Djedoe, Essia, Etimoe, European Cherry, European Poplar, European Walnut, Eveuss, Freijo, Garapa, Gerutu, Gombé rouge, Gombé towé, Gommier, Guariuba, Iatandza, Igaganga, Izombe, Jacareuba, Jequitiba, Kanda brun, Kanda rose, Kedondong, Kelat, Keledang, Keranji, Keruing, Kosipo, Kurokai, Landa, Limbali, Louro branco, and Macucu de paca.
• Liquid Behavior: Heartwood pores restrict deep fluid transit. Liquid penetrants and thin seal coats remain largely near the contact boundary, showing limited lateral or longitudinal intake into the solid wood grain.
• Shop Considerations: Builders cannot rely on deep inward soak to anchor finishes. Surface preparation must ensure that the wood face is free of milling residue and burnishing.

Class 4: Not Permeable Heartwood

• Representative Species: Abiurana vermelha, African canarium, Afzelia, Alan / Alan-Batu, Angelim vermelho, Ayan, Basralocus, Billian, Bintangor, Bitis, Black Guarea (Bossé Foncé), Chengal, Congotali, Cumaru / Tonka, Douka, Ebène veinée d’Asie, Ekki, European Larch, European Oak, European Sweet Chestnut, Eyoum, Gedu nohor, Giam, Haldu, Idigbo, Idéwa, Iroko, Itauba, Lati, Louro vermelho, and Makoré. (Species spanning Class 3-4 include African walnut, Alumbi, Ananta, Andok, Angelim amargoso, Anzèm / nténé, Cabreuva, Catucaém / louro faia, Ceylon Satinwood, Danta, European Spruce, Grenadillo / Grenadille d’Afrique, Kasai, and Macacauba).
• Liquid Behavior: Heartwood cellular structures are closed to liquid penetration. Preservatives, thin stabilizing fluids, and seal coats cannot travel past the immediate surface layer.
• Shop Considerations: Because fluid movement into the wood block is effectively blocked, the interface between the wood and an applied seal coat is purely superficial.

Wood	Heartwood treatability	Decay resistance
Abarco	Class 3 – poorly permeable	Durability class 3 – moderately durable
Abiurana vermelha	Class 4 – not permeable	Durability class 1 – very durable
Abura	Class 2 – moderately permeable	Durability class 5 – not durable
African Padauk	Class 2 – moderately permeable	Durability class 1 – very durable
African canarium	Class 4 – not permeable	Durability class 5 – not durable
African cordia	Class 3 – poorly permeable	Durability class 3 – moderately durable
African walnut	Class 3-4 – poorly or not permeable	Durability class 3 to 4 – moderately to poorly durable
Afzelia	Class 4 – not permeable	Durability class 1 – very durable
Agba	Class 3 – poorly permeable	Durability class 2 to 3 – durable to moderately durable
Alan / Alan-Batu	Class 4 – not permeable	Durability class 3 – moderately durable
Alep	Class 3 – poorly permeable	Durability class 1 – very durable
Alstonia	Class 1 – easily permeable	Durability class 5 – not durable
Alumbi	Class 3-4 – poorly or not permeable	Durability class 4 – poorly durable
Amesclào	Class 3 – poorly permeable	Durability class 2 – durable
Ananta	Class 3-4 – poorly or not permeable	Durability class 1 – very durable
Andok	Class 3-4 – poorly or not permeable	Durability class 2 – durable
Andoung	Class 2 – moderately permeable	Durability class 5 – not durable
Angelim amargoso	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Angelim pedra	Class 2 – moderately permeable	Durability class 3 – moderately durable
Angelim vermelho	Class 4 – not permeable	Durability class 1 – very durable
Angelin	Class 3 – poorly permeable	Durability class 2 – durable
Angoa	Class 3 – poorly permeable	Durability class 4 – poorly durable
Angueuk	Class 3 – poorly permeable	Durability class 2 – durable
Aningeria	Class 1 – easily permeable	Durability class 4 à 5 – poorly to not durable
Antiaris	Class 1 – easily permeable	Durability class 5 – not durable
Anzèm / nténé	Class 3-4 – poorly or not permeable	Durability class 5 – not durable
Araracanga	Class 3 – poorly permeable	Durability class 1 – very durable
Ariella	Class 3 – poorly permeable	Durability class 3 – moderately durable
Atlas Cedar	Class 3 – poorly permeable	Durability class 1-2 – very durable to durable
Ayan	Class 4 – not permeable	Durability class 3 – moderately durable
Baracara	Class 2 – moderately permeable	Durability class 3 – moderately durable
Basralocus	Class 4 – not permeable	Durability class 2 – durable
Batibatra	Class 3 – poorly permeable	Durability class 1 – very durable
Beli	Class 3 – poorly permeable	Durability class 3 – moderately durable
Benguet pine	Class 2 – moderately permeable	Durability class 4 – poorly durable
Berlinia	Class 3 – poorly permeable	Durability class 3 – moderately durable
Bilinga / Opepe	Class 2 – moderately permeable	Durability class 1 – very durable
Billian	Class 4 – not permeable	Durability class 1 – very durable
Bintangor	Class 4 – not permeable	Durability class 3 – moderately durable
Bitis	Class 4 – not permeable	Durability class 1-2 – very durable to durable
Black Guarea (Bossé Foncé)	Class 4 – not permeable	Durability class 2 – durable
Black wattle	Class 3 – poorly permeable	Durability class 3 to 4 – moderately to poorly durable
Bodioa	Class 1 – easily permeable	Durability class 5 – not durable
Brazil nut	Class 3 – poorly permeable	Durability class 3 – moderately durable
Brown sterculia	Class 3 – poorly permeable	Durability class 2 – durable
Cabreuva	Class 3-4 – poorly or not permeable	Durability class 1-2 – very durable to durable
Canon ball	Class 1 – easily permeable	Durability class 5 – not durable
Capomo	Class 1 – easily permeable	Durability class 5 – not durable
Cardeiro / Cedrinho	Class 3 – poorly permeable	Durability class 2 to 3 – durable to moderately durable
Catucaém / louro faia	Class 3-4 – poorly or not permeable	Durability class 2 to 3 – durable to moderately durable
Cedrinho	Class 2 – moderately permeable	Durability class 3 – moderately durable
Cedrorana	Class 2-3 – poorly to moderately permeable	Durability class 3 – moderately durable
Ceiba	Class 1 – easily permeable	Durability class 5 – not durable
Cerejeira	Class 2 – moderately permeable	Durability class 3 – moderately durable
Ceylon Satinwood	Class 3-4 – poorly or not permeable	Durability class 1 – very durable
Chengal	Class 4 – not permeable	Durability class 1 – very durable
Coconut wood	Class 2-3 – poorly to moderately permeable	Durability class 5 – not durable
Congotali	Class 4 – not permeable	Durability class 1 – very durable
Copaiba	Class 3 – poorly permeable	Durability class 5 – not durable
Coula	Class 3 – poorly permeable	Durability class 1 – very durable
Cow tree	Class 1 – easily permeable	Durability class 5 – not durable
Cryptomeria	Class 2(v)-3(v) – poorly to moderately permeable ("v" = variable)	Durability class 2 (v) – durable ("v" = variable)
Cumaru / Tonka	Class 4 – not permeable	Durability class 1 – very durable
Cupiuba	Class 2 – moderately permeable	Durability class 3 – moderately durable
Curupixa	Class 2 – moderately permeable	Durability class 4 – poorly durable
Dabema	Class 3 – poorly permeable	Durability class 3 – moderately durable
Dakama	Class 2 – moderately permeable	Durability class 3 – moderately durable
Dalli	Class 1-2 – moderately to easily permeable	Durability class 5 – not durable
Danta	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Diania	Class 1 – easily permeable	Durability class 5 – not durable
Difou	Class 3 – poorly permeable	Durability class 1 – very durable
Dina	Class 3 – poorly permeable	Durability class 1 – very durable
Djedoe	Class 3 – poorly permeable	Durability class 4 – poorly durable
Douka	Class 4 – not permeable	Durability class 1 – very durable
Dukali / amapa	Class 2 – moderately permeable	Durability class 5 – not durable
Durian	Class 2 – moderately permeable	Durability class 4 à 5 – poorly to not durable
East african bombax	Class 1 – easily permeable	Durability class 5 – not durable
Ekki	Class 4 – not permeable	Durability class 2 – durable
Ekop	Class 2 – moderately permeable	Durability class 3 – moderately durable
Ekoune	Class 1 – easily permeable	Durability class 5 – not durable
Erimado	Class 1 – easily permeable	Durability class 5 – not durable
Essia	Class 3 – poorly permeable	Durability class 3 – moderately durable
Etimoe	Class 3 – poorly permeable	Durability class 3 – moderately durable
European Ash	Class 2 – moderately permeable	Durability class 5 – not durable
European Beech	Class 1 – easily permeable	Durability class 5 – not durable
European Cherry	Class 3 – poorly permeable	Durability class 5 – not durable
European Larch	Class 4 – not permeable	Durability class 3 to 4 – moderately to poorly durable
European Oak	Class 4 – not permeable	Durability class 2 – durable
European Poplar	Class 3 – poorly permeable	Durability class 5 – not durable
European Silver Fir	Class 2-3 – poorly to moderately permeable	Durability class 4 – poorly durable
European Spruce	Class 3-4 – poorly or not permeable	Durability class 4 – poorly durable
European Sweet Chestnut	Class 4 – not permeable	Durability class 2 – durable
European Walnut	Class 3 – poorly permeable	Durability class 3 – moderately durable
Eveuss	Class 3 – poorly permeable	Durability class 1 to 2 (v) – very durable to durable ("v" =
Eyoum	Class 4 – not permeable	Durability class 1 – very durable
Faveira	Class 2 – moderately permeable	Durability class 5 – not durable
Freijo	Class 3 – poorly permeable	Durability class 2 – durable
Garapa	Class 3 – poorly permeable	Durability class 3 – moderately durable
Gedu nohor	Class 4 – not permeable	Durability class 3 – moderately durable
Geronggang	Class 1 – easily permeable	Durability class 5 – not durable
Gerutu	Class 3 – poorly permeable	Durability class 3 – moderately durable
Gheombi	Class 2 – moderately permeable	Durability class 3 – moderately durable
Giam	Class 4 – not permeable	Durability class 1 – very durable
Goiabao	Class 2 – moderately permeable	Durability class 4 – poorly durable
Gombé rouge	Class 3 – poorly permeable	Durability class 4 (v) – poorly durable ("v" = variable)
Gombé towé	Class 3 – poorly permeable	Durability class 3 (v) – moderately durable ("v" = variable)
Gommier	Class 3 – poorly permeable	Durability class 5 – not durable
Grenadillo / Grenadille d’Afrique	Class 3-4 – poorly or not permeable	Durability class 1 – very durable
Guanacaste	Class 1 – easily permeable	Durability class 5 – not durable
Guariuba	Class 3 – poorly permeable	Durability class 3 – moderately durable
Haldu	Class 4 – not permeable	Durability class 3 – moderately durable
Iatandza	Class 3 – poorly permeable	Durability class 2 – durable
Idigbo	Class 4 – not permeable	Durability class 2 to 3 – durable to moderately durable
Idéwa	Class 4 – not permeable	Durability class 1 – very durable
Igaganga	Class 3 – poorly permeable	Durability class 5 – not durable
Ilomba	Class 1 – easily permeable	Durability class 5 – not durable
Iroko	Class 4 – not permeable	Durability class 1-2 – very durable to durable
Itauba	Class 4 – not permeable	Durability class 1 – very durable
Izombe	Class 3 – poorly permeable	Durability class 2 – durable
Jacaranda	Class 1 – easily permeable	Durability class 5 – not durable
Jacareuba	Class 3 – poorly permeable	Durability class 2 – durable
Jelutong	Class 1 – easily permeable	Durability class 5 – not durable
Jequitiba	Class 3 – poorly permeable	Durability class 3 – moderately durable
Kanda brun	Class 3 – poorly permeable	Durability class 2 – durable
Kanda rose	Class 3 – poorly permeable	Durability class 2 – durable
Kapokier	Class 1 – easily permeable	Durability class 5 – not durable
Kasai	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Kauri	Class 2 – moderately permeable	Durability class 3 to 4 – moderately to poorly durable
Kedondong	Class 3 – poorly permeable	Durability class 5 – not durable
Kelat	Class 3 – poorly permeable	Durability class 3 – moderately durable
Keledang	Class 3 – poorly permeable	Durability class 3 – moderately durable
Kembang semangkok	Class 1 – easily permeable	Durability class 3 – moderately durable
Keranji	Class 3 – poorly permeable	Durability class 3 – moderately durable
Keruing	Class 3 – poorly permeable	Durability class 3 – moderately durable
Kosipo	Class 3 – poorly permeable	Durability class 2 to 3 – durable to moderately durable
Kumbi	Class 1 – easily permeable	Durability class 5 – not durable
Kurokai	Class 3 – poorly permeable	Durability class 5 – not durable
Landa	Class 3 – poorly permeable	Durability class 2 – durable
Lati	Class 4 – not permeable	Durability class 3 – moderately durable
Limbali	Class 3 – poorly permeable	Durability class 2 – durable
Longui	Class 2 – moderately permeable	Durability class 4 – poorly durable
Louro branco	Class 3 – poorly permeable	Durability class 4 – poorly durable
Louro vermelho	Class 4 – not permeable	Durability class 2 – durable
Macacauba	Class 3-4 – poorly or not permeable	Durability class 2 – durable
Macassar Ebony (Ebène Veinée d’Asie)	Class 4 – not permeable	Durability class 1 – very durable
Macucu de paca	Class 3 – poorly permeable	Durability class 1 – very durable
Magas	Class 2 – moderately permeable	Durability class 5 – not durable
Makoré	Class 4 – not permeable	Durability class 1 – very durable
Mambode	Class 2 – moderately permeable	Durability class 3 – moderately durable
Manchiche	Class 4 – not permeable	Durability class 1 – very durable
Mandioqueira	Class 2 – moderately permeable	Durability class 3 – moderately durable
Mango (Machang)	Class 1 – easily permeable	Durability class 5 – not durable
Manil / Manni	Class 3 – poorly permeable	Durability class 3 – moderately durable
Manilkara	Class 4 – not permeable	Durability class 1 – very durable
Manniballi	Class 3 – poorly permeable	Durability class 1 – very durable
Mansonia	Class 4 – not permeable	Durability class 1 – very durable
Maporokon	Class 3-4 – poorly or not permeable	Durability class 4 – poorly durable
Maritime Pine	Class 4 – not permeable	Durability class 3 to 4 – moderately to poorly durable
Marupa	Class 1 – easily permeable	Durability class 5 – not durable
Massaranduba	Class 4 – not permeable	Durability class 1 – very durable
Mecrussé	Class 4 – not permeable	Durability class 1 – very durable
Melancieira	Class 3 – poorly permeable	Durability class 2 – durable
Melunak	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Mengkulang	Class 3 – poorly permeable	Durability class 4 – poorly durable
Merawan	Class 4 – not permeable	Durability class 2 to 3 – durable to moderately durable
Merbau	Class 4 – not permeable	Durability class 1-2 – very durable to durable
Merkus pine	Class 2 – moderately permeable	Durability class 4 – poorly durable
Merpauh	Class 2 – moderately permeable	Durability class 5 – not durable
Mersawa	Class 3-4 – poorly or not permeable	Durability class 4 – poorly durable
Moabi	Class 3-4 – poorly or not permeable	Durability class 1 – very durable
Mora	Class 3-4 – poorly or not permeable	Durability class 1 – very durable
Moral	Class 4 – not permeable	Durability class 1 – very durable
Morototo	Class 1 – easily permeable	Durability class 5 – not durable
Mountain Pine (Hooked Pine)	Class 3 – poorly permeable	Durability class 4 – poorly durable
Mubala	Class 3-4 – poorly or not permeable	Durability class 1-2 – very durable to durable
Muhuhu	Class 4 – not permeable	Durability class 1 – very durable
Muirapiranga / Bloodwood	Class 4 – not permeable	Durability class 2 – durable
Mukulungu	Class 3 – poorly permeable	Durability class 1 – very durable
Mumuli	Class 2 – moderately permeable	Durability class 5 – not durable
Musizi	Class 1 – easily permeable	Durability class 4 – poorly durable
Mutenye	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Niangon	Class 4 – not permeable	Durability class 3 – moderately durable
Nieuk	Class 2 – moderately permeable	Durability class 4 – poorly durable
Niove	Class 4 – not permeable	Durability class 1 – very durable
Nyatoh	Class 3 – poorly permeable	Durability class 3 – moderately durable
Oboto	Class 3 – poorly permeable	Durability class 2 – durable
Odoko	Class 1 – easily permeable	Durability class 5 – not durable
Ogea	Class 2-3 – poorly to moderately permeable	Durability class 4 à 5 – poorly to not durable
Ohia	Class 1 – easily permeable	Durability class 5 – not durable
Okan	Class 4 – not permeable	Durability class 1 – very durable
Okwen	Class 3 – poorly permeable	Durability class 3 – moderately durable
Olon	Class 2-3 – poorly to moderately permeable	Durability class 3 – moderately durable
Olène	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Onzabili	Class 2 – moderately permeable	Durability class 5 – not durable
Osanga	Class 2-3 – poorly to moderately permeable	Durability class 2 – durable
Ossabel	Class 3 – poorly permeable	Durability class 3 – moderately durable
Ossimiale	Class 3 – poorly permeable	Durability class 4 – poorly durable
Ossoko	Class 2 – moderately permeable	Durability class 5 – not durable
Ovangkol	Class 3 – poorly permeable	Durability class 2 – durable
Ovoga	Class 1 – easily permeable	Durability class 3 – moderately durable
Owui	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Ozigo	Class 3 – poorly permeable	Durability class 5 – not durable
Ozouga	Class 4 – not permeable	Durability class 1 – very durable
Padauk amboina	Class 3-4 – poorly or not permeable	Durability class 1 – very durable
Pakuri	Class 3 – poorly permeable	Durability class 2 – durable
Pashaco / paricá	Class 1 – easily permeable	Durability class 5 – not durable
Patula pine	Class 1 – easily permeable	Durability class 5 – not durable
Pau marfim	Class 1 – easily permeable	Durability class 3 – moderately durable
Pau mulato	Class 3 – poorly permeable	Durability class 3 – moderately durable
Perupok	Class 2 – moderately permeable	Durability class 4 – poorly durable
Peruvian Walnut	Class 2-3 – poorly to moderately permeable	Durability class 3 – moderately durable
Piquia	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Piquiarana	Class 3 – poorly permeable	Durability class 2 – durable
Preciosa	Class 4 – not permeable	Durability class 1 – very durable
Pterygota	Class 1 – easily permeable	Durability class 5 – not durable
Pucté	Class 4 – not permeable	Durability class 1 – very durable
Pulai	Class 1 – easily permeable	Durability class 5 – not durable
Punah	Class 3 – poorly permeable	Durability class 3 – moderately durable
Pyinkado	Class 4 – not permeable	Durability class 1 – very durable
Pyinma	Class 3 – poorly permeable	Durability class 3 – moderately durable
Quaruba	Class 3 – poorly permeable	Durability class 4 – poorly durable
Radiata Pine (European Plantation)	Class 2-3 – poorly to moderately permeable	Durability class 4 à 5 – poorly to not durable
Red balau	Class 4 – not permeable	Durability class 3 to 4 – moderately to poorly durable
Red grandis	Class 3-4 – poorly or not permeable	Durability class 2 to 4 – durable to poorly durable
Rengas	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Resak	Class 4 – not permeable	Durability class 2 – durable
Rosewood Para	Class 4 – not permeable	Durability class 1 – very durable
Rubberwood	Class 1 – easily permeable	Durability class 5 – not durable
Safukala	Class 3 – poorly permeable	Durability class 4 – poorly durable
Sandbox	Class 1 – easily permeable	Durability class 5 – not durable
Sapucaia	Class 4 – not permeable	Durability class 1 – very durable
Scented Guarea (Bossé Clair)	Class 4 – not permeable	Durability class 2 – durable
Scots Pine	Class 3-4 – poorly or not permeable	Durability class 3 to 4 – moderately to poorly durable
Senegal mahogany	Class 3 – poorly permeable	Durability class 3 – moderately durable
Sepetir	Class 3 – poorly permeable	Durability class 2 – durable
Sesendok	Class 1 – easily permeable	Durability class 5 – not durable
Simpoh	Class 1 – easily permeable	Durability class 5 – not durable
Snakewood	Class 3 – poorly permeable	Durability class 3 – moderately durable
Sonokeling Rosewood	Class 4 – not permeable	Durability class 1 – very durable
Sougué	Class 2 – moderately permeable	Durability class 4 – poorly durable
Sterculia	Class 1 – easily permeable	Durability class 5 – not durable
Sumauma	Class 1 – easily permeable	Durability class 5 – not durable
Suren	Class 3-4 – poorly or not permeable	Durability class 3 to 4 – moderately to poorly durable
Sycamore Maple (Great Maple)	Class 1 – easily permeable	Durability class 5 – not durable
Tali / Missanda	Class 4 – not permeable	Durability class 1 – very durable
Tamalan Rosewood	Class 4 – not permeable	Durability class 1 – very durable
Tamarindo (Groçai-rosa)	Class 3-4 – poorly or not permeable	Durability class 1-2 – very durable to durable
Tanimbuca	Class 3 – poorly permeable	Durability class 3 – moderately durable
Tasmanian oak	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Tatajuba	Class 3 – poorly permeable	Durability class 1 – very durable
Tauari	Class 1 – easily permeable	Durability class 5 – not durable
Tchitola	Class 3-4 – poorly or not permeable	Durability class 3 – moderately durable
Timborana	Class 3 – poorly permeable	Durability class 3 – moderately durable
Uchy	Class 3 – poorly permeable	Durability class 3 to 4 – moderately to poorly durable
Utile	Class 4 – not permeable	Durability class 2 to 3 – durable to moderately durable
Vésámbata	Class 4 – not permeable	Durability class 1 – very durable
Vêne	Class 4 – not permeable	Durability class 1 – very durable
Wacapou	Class 3 – poorly permeable	Durability class 1 – very durable
Wallaba	Class 4 – not permeable	Durability class 1 – very durable
Wamara	Class 4 – not permeable	Durability class 1 – very durable
Wamba	Class 4 – not permeable	Durability class 1-2 – very durable to durable
Wenge	Class 4 – not permeable	Durability class 2 – durable
White seraya	Class 3 – poorly permeable	Durability class 4 – poorly durable
White sterculia	Class 3-4 – poorly or not permeable	Durability class 4 – poorly durable
Yellow balau	Class 4 – not permeable	Durability class 2 – durable
Yellowheart	Class 3-4 – poorly or not permeable	Durability class 1 – very durable
Yemane	Class 3 – poorly permeable	Durability class 4 – poorly durable
Zebrano	Class 3 – poorly permeable	Durability class 3 – moderately durable

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

Why Not-Permeable Woods Require Different Surface Prep

The stark contrast between Class 1 and Class 4 timbers dictates how a tabletop maker prepares raw wood edges before applying liquid sealers or bonding resins. When wood is easily permeable, liquid resin or seal coats travel into the open pores, solidifying within cellular voids to create deep mechanical interlocks. This absorption means surface irregularities are somewhat forgiving, though the builder must monitor for hungry patches and bubbling caused by displaced internal air.

In not-permeable timbers, however, liquids cannot enter the cellular matrix. Because no deep mechanical roots form within the heartwood, adhesion relies entirely on the outermost boundary. As a result, surface preparation for Class 4 species demands strict mechanical discipline:

• Mechanical Abrasion: Smooth planed or burnished surfaces provide little grip for viscous resins. Because seal coats cannot sink inward, the face and live edges must be sanded thoroughly with clean abrasives to create microscopic texture. This provides the physical profile necessary for strong adhesion.
• Pore Clearing and Debris Removal: Fine sanding dust lodged in closed pores acts as a barrier. On permeable wood, thin liquids can sometimes bypass loose dust, but on not-permeable wood, dust prevents the liquid from ever contacting the solid wood fiber. Builders should remove all dry particles using clean compressed air, vacuuming, or wiping as recommended by product instructions.
• Managing Surface Contaminants: Dense, non-permeable heartwoods often contain natural resins, oils, or waxes that actively repel liquid coats. Wiping the surface with a suitable solvent prior to coating ensures that the boundary layer is clean and free of oils that would otherwise cause liquid beads or poor bond strength.
• Observing Manufacturer Guidelines: Because resin penetration is negligible on Class 4 woods, table builders must follow the resin maker’s technical data sheet for open times, recoat windows, and surface scuffing steps to ensure the strongest possible bond.

Sources

• CIRAD Tropix 7 technical sheets (index)

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

Header image: original graphic by BigEpoxy.com.