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fill nicks and scratches on polyurethane for painting

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Forum topic by SteveT posted 08-26-2019 06:19 PM 491 views 0 times favorited 9 replies Add to Favorites Watch
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SteveT

38 posts in 1750 days


08-26-2019 06:19 PM

I picked up (literally) a free bureau that is pine with what appears to be a polyurethane finish. I intend to paint over the poly using General Finishes milk paint. The piece is very sound structurally, but there are many nicks and scratches all over it. It also has a lot of rounded over edges on the top and all of the drawers. Sanding out those scratches would take a long time.

Is there a putty that I could spread over the nicks and scratches of the poly finish, then do a light sanding to smooth out the putty to match the original contours? Then finish it off with paint.


9 replies so far

View LesB's profile

LesB

2201 posts in 3950 days


#1 posted 08-26-2019 07:02 PM

Being as you are painting over I would get some Bondo (auto body filler).

-- Les B, Oregon

View DrDirt's profile

DrDirt

4592 posts in 4249 days


#2 posted 08-26-2019 07:34 PM

Yep. Auto products here. For smaller scratches and such a tube of glazing compound

-- “The two most important days in your life are the day you are born and the day you find out why.” Mark Twain

View 4wood's profile

4wood

34 posts in 460 days


#3 posted 08-26-2019 09:11 PM

I just finished a computer desk top in a similar condition. I filled the deeper nicks with glazing compound and sanded it smooth. Then I put on several coats of primer letting it build up and then hand sanded it smooth with a flat backing block and sandpaper. The primer I used was was Zinnser. The type of glazing putty I used comes in a toothpaste type tube and is applied to the surface nicks with a plastic squeegee and dries very quickly. I believe this is one that is similar.

https://www.walmart.com/ip/Bondo-Glazing-and-Spot-Putty-00907ES-4-5-oz-1-Tube/16927984?sourceid=csebr038237c7ecf8714c4c9701ac8714e17ccf&wmlspartner=bizratecom&affcmpid=3557163035&tmode=0000&veh=cse&szredirectid=15668529608504872067510080302008005

View John Smith's profile

John Smith

2013 posts in 669 days


#4 posted 08-26-2019 11:32 PM

.

-- I am a painter. That's what I do. I paint things --

View SteveT's profile

SteveT

38 posts in 1750 days


#5 posted 08-27-2019 12:07 AM

Thanks for all of the feedback.

I’ve been sanding the flat areas before putting the bondo (or glazing) on. Am I wasting my time? I mean, should I put the bondo on the smooth poly surface, then sand smooth? I’m thinking that a roughed up surface would be better for the bondo, but don’t have any experience with this.

View John Smith's profile

John Smith

2013 posts in 669 days


#6 posted 08-27-2019 11:54 AM

Bondo has a very tenacious adhesive property.
it will STICK to just about any raw wood, painted or metal surface with very little prep.
I normally fill defects prior to sanding. spot priming with an automotive primer
before painting may be necessary to assure even coverage of the top coats.
some people use drywall joint compound with good results as it
is also very aggressive in nature as a filler. (but, it is much softer).
Note: Bondo is basically a polyester resin liquid with a filler.
over time, the filler will settle to the bottom, just like paint, but much thicker.
so it is important to firmly STIR Bondo occasionally all the way to the bottom
with a stick ~ not just the top half of the product.
clean up with acetone.

and to clarify on “glazing putty”; it is not the type that is used for setting window panes.
it is an automotive product for filling small scratches in paint that are less that 1/32” deep.
scratches deeper than 1/32” should be filled with Bondo Body Filler.

and the vintage can opener is an excellent tool for opening up small scratches for better filling.

.

-- I am a painter. That's what I do. I paint things --

View SteveT's profile

SteveT

38 posts in 1750 days


#7 posted 08-30-2019 01:23 AM

I’m still working on this project. We are painting the top a different color than the rest of it. I sprayed 4 coats on the top today and might finish the rest tomorrow. Weekend plans may squash that idea though.

I used the Bondo spot putty/glazing for most of it. I did mix up a batch of regular Bondo once, but it dries so fast that it wasn’t practical to fill in random nicks and scratches all over the piece. By the time I worked on one small area, the Bondo had dried. I could’ve kept mixing up smaller batches, but took the easy way out instead.

The spot putty sands easier and the regular Bondo seems to be harder. Hopefully the spot putty will hold up.

View a1Jim's profile

a1Jim

117721 posts in 4084 days


#8 posted 08-30-2019 02:14 AM

For light scratches and small dents, I think Bondo has too much body and adds lots of sanding time, for painted surfaces I would recommend some drywall compound, this is faster and much easier to sand.

https://www.artisticwoodstudio.com/videos

View Aj2's profile

Aj2

2480 posts in 2304 days


#9 posted 08-30-2019 02:20 AM

Generals milk paint is pretty thick stuff. Unless the scratches are more like gouges I’d wager you won’t need to fill them.

Good Luck

-- Aj

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