Modification of Shellac with Clove (Eugenia caryophyllata) and Thyme (Satureja hortensis) Essential Oils: Compatibility Issues and Effect on the UV Light Resistance of Wood Coated Surfaces

Shellac (SL) is a natural resin employed for wood finishing, while clove (Eugenia caryophyllata) and thyme (Satureja hortensis) essential oils (C-EO, T-EO) are organic products of vegetal origin with antifungal, antimicrobial antioxidant properties. The present paper aims at exploring the potential modifying alcoholic shellac solutions T-EO), focussing on recurrent effects this modification traditional finishing technique, colour UV light resistance coated surfaces. compatibility C-EO T-EO ethyl alcohol reference SL solution was evaluated, modified content 5% 10% were prepared. Wood samples European maple (Acer pseudoplatanus) walnut (Juglans regia) finished solutions. An accelerated ageing test run, evaluated after 24, 48 72 h exposure. Colour measurements in CIELab system FTIR–ATR investigation monitoring surface chemistry changes. Coating resulted visible changes both species (ΔE values 31.06 13.00 walnut) increased resistance, reducing exposure (by 83% by 59% as compared to uncoated controls. Modification only slightly influenced surfaces = 1.88–5.41 maple, ΔE 1.36–3.41 their resistance. (ΔE) varied range 1.63–4.53 2.39–3.58 walnut, being generally higher 1.7–2.9 units 0–1 unit FTIR highlighted minor chemical coating films A photo-induced oxidative process eugenol seemed possible case C-EO.