Influence of different veneer soaking technological factors on reaction to fire performance of birch plywood

A study of the influence of different technological factors on the reaction to fire performance of birch plywood made by the veneer soaking method was conducted and reported in this research paper. Technological parameters like the fire-retardant salt concentration level, temperature and soaking time were investigated to find the best technological parameters for manufacturing fire-retardant birch plywood. The aim of this work is to find the optimal technological parameters for manufacturing fire retardant birch plywood with the best possible reaction to fire class B-s1, d0 for wood-based products according to EN 13501-1. The soaking technology of each individual veneer before gluing was used for dry veneer soaking and wet veneer soaking by the diffusive impregnation method. A test plan matrix was created to find the relationship between the technological factors. The first experiment stage was investigation of fire-retardant concentration and soaking time of reaction to fire performance of birch plywood at 20 °C temperature liquid. In the second experiment, the influence of fire-retardant liquid heating was investigated by using three heating temperatures 30, 40 and 55 °C. Plywood samples were produced at an experimental scale using a laboratory press. Reaction to fire performance was measured by a single burning test method according to EN 13823, which is the main test method for evaluation of reaction to fire performance according to EN 13501-1. It was concluded that the duration of soaking and fire-retardant concentration has an influence on the reaction to fire performance of birch plywood. 8- and 16-hour duration was discovered as insufficient duration, while duration more than 24 hours did not show any significant improvement. It was concluded that higher concentration levels significantly improve the fire-retardant retention level in wood and heating also shows a positive impact on the fire protection level when temperatures do not exceed 50°C.