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Does Zinser spray shellac need to "cure", or is it done when it feels dry?

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Forum topic by HarveyDunn posted 04-04-2014 02:31 PM 1146 views 0 times favorited 9 replies Add to Favorites Watch
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HarveyDunn

328 posts in 1197 days


04-04-2014 02:31 PM

I’m going to spray some Zinser brand rattle can shellac onto a painted piece as a top coat. I’ll do 3 or 4 coats, then “rub it out” with scotchbrite and paste wax to knock off a bit of the gloss and make it more uniform.

Question: do I need to allow time for the shellac to “cure”? Or is it done when it feels dry to the touch?


9 replies so far

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woodchuckerNJ

1154 posts in 1100 days


#1 posted 04-04-2014 02:41 PM

You can lay on multiple coats with shellac after it is dry to the touch.
Rubbing out, I would wait a couple of days for the best finish. You can rub it with in 2 hours, should be ok, but it hardens better after 2 days, and will give you the best look. All finishes take time to really harden. When you rub them out early, they don’t look as good later, and will need to be done again if you are looking for a polished look. If you are looking for a satin look, you’ll be ok. (that’s the short version)

-- Jeff NJ

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HarveyDunn

328 posts in 1197 days


#2 posted 04-04-2014 02:45 PM

Definitely want the satin look.

If I throw caution to the wind and rush it a bit, and am not happy with the results, could I redo it in a few days? or would I need to remove it and start over it?

View Pezking7p's profile

Pezking7p

3097 posts in 1117 days


#3 posted 04-04-2014 02:47 PM

Since shellac isn’t crosslinking or doing anything chemical after it is applied, it is literally just drying on the surface.

There are varying degrees of “dry”. Shellac dries probably 90% within a few minutes, but the last 10% takes a day. Depends on temperature/humidity.

-- -Dan

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HarveyDunn

328 posts in 1197 days


#4 posted 04-04-2014 02:48 PM

65 degrees and bone dry here today.

View shampeon's profile

shampeon

1718 posts in 1649 days


#5 posted 04-04-2014 04:11 PM

The alcohol in wet shellac does melt into the previous layer, though, so it’s not quite true that it just sits on the surface. That’s why it’s easy to repair.

I would still wait a day before doing final rub out. Not-quite-cured shellac glazes your sandpaper, and that makes it hard to get an even surface.

-- ian | "You can't stop what's coming. It ain't all waiting on you. That's vanity."

View HorizontalMike's profile

HorizontalMike

7154 posts in 2380 days


#6 posted 04-04-2014 04:44 PM

Woodchucker NJ: ”...Rubbing out, I would wait a couple of days for the best finish. ...”

Harvey, I would take that suggestion even further out into the future. Depending on how many coats you have applied, waiting a week or more is NOT unheard of, and it serves to protect against prematurely damaging the finish when buffing.

For more information, read this thread. I learned the hard way:
http://lumberjocks.com/topics/50406

-- HorizontalMike -- "Woodpeckers understand..."

View Loren's profile

Loren

8313 posts in 3113 days


#7 posted 04-04-2014 04:59 PM

It depends on how exactly and to what gloss you want to
rub out the finish. There’s leveling to be done if you
want a flawless gloss finish… it’s generally not worth the
work on furniture where it’s generally acceptable to
top coat with paste wax and buff. I get rid of nibs and
bumps, rub out with synthetic steel wool and top coat
with wax. It gives an even, mellow sheen and is not
too time consuming.

For guitars and things like that where it isn’t appropriate
to use wax, the longer you let the finish harden the
more straightforward it becomes to level the finish and
rub out to a gloss.

I would give it 3 days with shellac, if you can bear to wait.
It’s not awful to do it after 12 or 24 hours with shellac
on furniture. I’ve done that. If you sand to level the
surface, go easily. If you cut all the way through the
shellac, making a repair is not so easy for a beginner.

View Fred Hargis's profile

Fred Hargis

3945 posts in 1959 days


#8 posted 04-04-2014 05:17 PM

Shellac doesn’t “cure”, it simply hardens once the solvents evaporate. While it’s dry enough for most stuff pretty quickly, waiting a day or 2 (or 3) wouldn’t hurt before trying to cut the gloss, especially with that many coats.

-- Our village hasn't lost it's idiot, he was elected to congress.

View gfadvm's profile

gfadvm

14940 posts in 2156 days


#9 posted 04-05-2014 01:35 AM

My rule of thumb is when 320 grit sanding produces fine white powder, it is ready to sand/rub out. Sand too soon and shellac really wants to ‘corn up’ your sandpaper.

-- " I'll try to be nicer, if you'll try to be smarter" gfadvm

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