how to seal leveling compound thats dust like? Help, advice, information, answers and tips on all types of flooring from laminate and carpet to timber and vinyl

[simonkbike]

I am laying amtico tiles in a bathroom and put new flooring down except for a small patch old hearth base about 1ft x 2ft.
I used some levelling compoud I found in back of garage from last year - went down ok and nice smooth finish.
Then when i was touching up the join. between compound and timber i found that while the surface is smooth it's easily broken and the underneath just rubs away as dust.
I know it's stingy but I'm unwilling to spend a fortune on such a smalll patch.
Any suggestions?

[welsh brickie]

you could mix some pva and paint it on, to seal the compound as for the crack, timber will expand and contract against concrete, so you could use expanding foam to fill the gap, if its quite wide, or a silicone sealant