Thanks guys It seems reasonable (very practical and affordable-90gr/~15₤) tinning powder from MEGA. It has also long shelf lifetime and very illuminative instructions on Farnell's web site. Just a little problem! That's I live in Kiev/Ukraine... I'm not sure but might be too expensive due to shipping/handling cost. Because Farnell sells only 450gr/44₤. But then I think, it worths to order either to MEGA or to Farnell.
Thanks again.