weak finish

[la Huerta]

hey all...


question regarding layering a finish, i'v done some experimenting and find that if i layer up say, shellac as a sealer, stain (black japan), then seal that with shellac and then something like floorproof as a finish, (allowing proper drying times of cause) i find the finish isn't very strong, i did the tape test and on one trial the tape pulled off the finish....

...so, what's going on here, something isn't binding, i need the shellac to seal the BJ and also seal the timber so the BJ floats over it and not into the grain creating a black mess...perhaps i may have applied the shellac too thick (although it wasn't actually that thick, but just thin enough to brush), perhaps there is too many smooth surfaces, each layer isn't 'keying in' the next so to speak ,could this cause adhesive problems?

any suggestions , anyone...?...pity please...

[echnidna]

is the black coming off with the tape?

[la Huerta]

hi mate...

no the BJ appears to stick (being tar based), it seems to be after that...

[echnidna]

you need to run tests on some scrap.

I suspect the problem is either
shellac over black
or more likely floorproof over the shellac

[la Huerta]

yeh i reckon floorproof over the shellac...i have to seal the BJ pretty well to stop it bleeding into the topcoat, so the FP must to be adhering to the shellac...what else could i use, i don't like poly (to plastic), what is used by other forum members over shellac , maybe danish oil , i really need a protective topcoat , rather than just shellac , hard shellac is too pricey for the amount i'd go through...

[echnidna]

Try using satin poly over the shellac, applied with a pad (in a similar way to french polish)
It gives you a fine yet good looking hard wearing finish.

[la Huerta]

cheers mate, i'll give it a whirl, i'v run out of floorproof anyway, that stuff has such a short shelf life, i had a half a tin left, a couple of weeks later it was lumpy, it goes off a soon after you open the tin...