Harry Muscle wrote:
We just had our hardwood floors refinished (and stained) with four
coats of oil modified urethane. Does anyone know how long it takes for=

this kind of urethane to reach it's full strengh. I'm hoping to stay
off the floor until it's fully cured ... unless it takes months
=20
Thanks,
Harry
=20

Oil/Varnish (urethane) finishes are Reactive Curing finishes -- they=20
bond with oxygen, or there is a catalyst in the mix -- so when the=20
thinner evaporates a reaction occurs... Cross-linking or polymerization..=
=2E


I suspect it is oxygen curing -- cures from the top down -- so If the=20
coats are thick (brushed on), I would treat it gently for a month... But =

that's an _opinion_ -- no facts to base it on till you give more info -- =

just a suggestion that has a wide safety margin.

You did not specify the brand or the exact type -- so at best people=20
could only guess -- since they have no info on the type.

You got some good advice to call the manufacturer, or look up their web=20
site -- since there is a fair bit of variation in curing times.

Get understanding Wood finishing by Bob Flexner if you want more detail=20
than you could ever wish for.


--=20
Will R.
Jewel Boxes and Wood Art
http://woodwork.pmccl.com
The power of accurate observation is commonly called cynicism by those=20
who have not got it.=94 George Bernard Shaw

OK, I'm gonna try to call the manufacturer ... however in the mean
time, here's some more information I pulled from the MSDS ...

It's made by Torcan Coatings (www.torcancoatings.com) and it's called
Gymnasium Satin. It's an oil modified polyurethane from the aliphatic
hydrocarbon chemical family. It's 53% mineral spirts and 9% Silica
Amorphous. I'm not sure if this info actually helps anyone, but you
guys wanted more info.

Thanks,
Harry

Harry Muscle wrote:
OK, I'm gonna try to call the manufacturer ... however in the mean
time, here's some more information I pulled from the MSDS ...
=20
It's made by Torcan Coatings (www.torcancoatings.com) and it's called
Gymnasium Satin. It's an oil modified polyurethane from the aliphatic
hydrocarbon chemical family. It's 53% mineral spirts and 9% Silica
Amorphous. I'm not sure if this info actually helps anyone, but you
guys wanted more info.
=20
Thanks,
Harry
=20

From...
http://www.woodworking.com/wwtimes_oilvarnish.cfm

************************************************** ***
One very important factor when applying varnish is how the temperature=20
effects the speed at which it cures. You should not apply varnish in=20
temperatures lower than 65 degrees. If you apply varnish in lower=20
temperatures it may take several days, even weeks for it to cure. Room=20
Temp. (approx. 70 to 75 degrees) is good for applying varnish. Hotter=20
temps. will make the varnish cure quicker, but the solvent in the=20
varnish will evaporate quicker, making the varnish set-up quickly and=20
you may have a problem getting the varnish to flow out properly. This=20
could result in brush marks, bubbles and an uneven film. When working in =

temperatures higher than 75 degrees, try not to work on large surfaces.
************************************************** **8

Nobody seems to mention specific times -- because...

Temperature ***
Humidity
Thickness o application layer
and Exact oil/varnish ratio
sanded between coats?

all make a difference.

I stick with my guess of about a month for close to max. hardness. But=20
it's a _guess_

I am guessing that they brushed it on and had to work quickly -- so the=20
there was not much oil... It should dry harder if so.


Certainly no less than a week...




http://www.michaels.com/art/online/d...leNum=3Dae0119
"Let the varnish cure for several days before placing anything heavy on=20
it so as to prevent any dents being made in the finish. It is a good=20
idea to wipe a coat of clear paste wax on the bottom of any painted=20
object that is placed on the finished project, as this will prevent the=20
two sticking together."


http://www.google.ca/search?q=3Dvarn...3Dsxm&lr =3D=
&client=3Dfirefox-a&rls=3Dorg.mozilla:en-USfficial_s&start=3D10&sa=3DN


--=20
Will R.
Jewel Boxes and Wood Art
http://woodwork.pmccl.com
The power of accurate observation is commonly called cynicism by those=20
who have not got it.=94 George Bernard Shaw