The matter of low price of amino resins and simplicity of modification process in comparison with methods based on polymerization of monomer impregnated wood is also important.

Changes in physical and mechanical properties of amino resins modified wood like: hardness, dimension stabilization (swelling), absorption, resistant for biological factors activity and so on are closely connected with resins content in wood.

The method applied in research of resins destination in wood using ultrasounds allows size the dependence between speed of oblong ultrasound wave flow and resins contents in wood. In research tester type UNIPAN 540 has been used to measure speed flow of waves frequency from 10 kHz up 1 MHz with accuracy of measurement 0. 1 us. Tested samples were modified with 5 different solutions of amino resins and water ( NH OH hardener ITD technology *).

The research stated that:

• together with rise of amino resins contents in wood the speed of flow of ultrasound waves grows down,
• the higher accuracy of waves the lower flow speed in tested samples.
• the highest speed of waves flow has been noticed in pine. birch and alder wood; the lowest speed in poplar wood,
• the higher solution of resin in water used for impregnation the lower flow speed of ultrasound waves in wood samples having similar result degree of amino resins modification,
• the speed of waves grows together with the distance from log's centre heart as well as the length of traheid.