Sealing the grain with car putty.

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Forum topic by lanwater posted 07-16-2011 08:23 AM 6161 views 1 time favorited 37 replies Add to Favorites Watch
View lanwater's profile


3111 posts in 3133 days

07-16-2011 08:23 AM

During a recent trip, I saw a finisher use car putty all over a bed he was finishing.
2 days later, after it dried, he sanded it, cleaned the dust.

a couple of hours later he started spray painting.

The final product looked great. The finish was flawlessly smooth.

Anyone ever used this method?

How does the car putty hold on wood in the long run? I wood think the residual humidity in the wood might cause it to peel.

-- Abbas, Castro Valley, CA

37 replies so far

View Dennisgrosen's profile


10880 posts in 3314 days

#1 posted 07-16-2011 09:30 AM

sound a little werd to me Ian
since ´product´s for metl is very hard in the way it can´t move with the wood
as I know of …....... but my only knowledge about it is becourse the former owner
off our house had used paint on the windows that normaly is used on ships and they
are oilbased i don´t know about the newr waterbased paints they use in the car industry today
if they are more flexiple


View papadan's profile


3584 posts in 3567 days

#2 posted 07-16-2011 12:07 PM

If your wood is sanded, then you can get the same kind of super smooth paint finish by just priming first and fine sanding the primer.

View William's profile


9950 posts in 3041 days

#3 posted 07-16-2011 01:32 PM

I have seen contractors years ago fix termite damage with car putty (bondo). They used drills, saws, and whatever they needed to remove all damage from some posts they were fixing under an old porch. Then they filled it with bondo. They let it sit a few days and then come back, sanded and painted it.
Like you, I noticed it looked good. However, I was only there to fix the roof. I have no idea what the long term results were.


View ScottN's profile


261 posts in 2879 days

#4 posted 07-16-2011 01:42 PM

I’ve used sheet rock compound for the edge of MDF. I would put a thin layer on, forcing it into the grains with a little pressure and 2 hours later I would sand it off. Works great for painting.

-- New Auburn,WI

View Uncle_Salty's profile


183 posts in 3272 days

#5 posted 07-16-2011 02:19 PM

I have used “bondo” to repair window sills and whatnot from time to time. You can adjust the drying time by varying the amount of hardener you add to the mix. Very similar to using epoxy, except bondo is a lot cheaper! But be warned: Bondo is a little “fumey.” You had better be in a well ventilated area when using it.

Drywall mud is great for the edges of mdf. That is a great tip.

View Earlextech's profile


1162 posts in 2890 days

#6 posted 07-16-2011 02:50 PM

The idea of using Bondo to fill problems areas, under a painted finish, has been around for years. I was doing it at least 30 years ago and I’m sure I wasn’t the first. Also, never had any customer call with any issues related to it.

-- Sam Hamory - The project is never finished until its "Finished"!

View RobertT's profile


70 posts in 2980 days

#7 posted 07-16-2011 03:25 PM

I have used bondo to fill grain on a painted project. Works great. The only problem I had was it cured way to fast. I am sure that was user error.

View rance's profile


4266 posts in 3359 days

#8 posted 07-16-2011 03:32 PM

Dennis, unless you put a ‘continuous layer’ on, the expansion and contraction won’t be a problem. Simply filling pores is generally ok.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View CharlieM1958's profile


16281 posts in 4417 days

#9 posted 07-16-2011 03:47 PM

As others have noted, using bondo on wood is fairly common. It’s great for painted applications, but I wouldn’t want to try staining it. :-)

-- Charlie M. "Woodworking - patience = firewood"

View Planeman40's profile


1307 posts in 2960 days

#10 posted 07-16-2011 04:22 PM

A while back I bought some glass-paned wood doors to be assembled to replace a wide sliding glass door. These came from a surplus place. The doors appeared to be new doors that had an error in the placement of the holes drilled for the door knob units. I used Bondo to fill in the holes and then used a belt sander to sand down the filled in areas. The doors were painted and now after seven years of use with one side exposed to the weather the filled in spots are still undetectable.

I have also used Bondo to fill in other imperfections in doors and other wood items bought from surplus suppliers and all applications have worked very well as long as you are painting over the repaired area. You can’t even see the repair if it is sanded well before painting. The repair holds up well too.


-- Always remember: It is a mathematical certainty that half the people in this country are below average in intelligence!

View Lee Barker's profile

Lee Barker

2170 posts in 3049 days

#11 posted 07-16-2011 05:15 PM

Bondo is great stuff. If it can withstand the movement of metal and extremes of temperature typical of most cars, it’s good for wood. I keep it around.

The conundrum is how much to buy. Large amount is significantly cheaper by the pound, but if you don’t use it, it gets, well, useless. Maybe the small size is a better buy.

Tip: If your hardener dries up and the paste is still good, drop by your local auto body supply place. A little chat and you may well walk out with a free or cheap tube of hardener alone.



-- " his brain, which is as dry as the remainder biscuit after a voyage, he hath strange places cramm'd with observation, the which he vents in mangled forms." --Shakespeare, "As You Like It"

View Loren's profile


10477 posts in 3847 days

#12 posted 07-16-2011 06:19 PM

I have seen it used and used it for paint grade work and it works
very well. It doesn’t seem to shrink too much. I suppose it
can be tinted darker as a grain filler, but there are other options
that involve less toxicity and are simpler to use.

View Spoontaneous's profile


1334 posts in 3529 days

#13 posted 07-16-2011 06:46 PM

Yeah, bondo is good all around stuff. There is very similar product that I like even better. It is a stone adhesive with the trade name Akemi and they use it to fill in holes in marble and granite. They have a couple of different formulas…. the ‘knife grade’ which has a finer texture than the bondo and comes in transparent, white and buff color. The other is a ‘flowing’ grade and I don’t remember if it is available in the buff color, but it is in white and transparent.

Like I said, it has a finer texture and you can pigment it any color or tint that you want. We used it for stone but also on fiberglass, acrylic, cultured marble, stone, etc. Same as the bondo you kick it off with a catalyst (paste or liquid). In any case, it sands to a fine finish and can even be polished with compounds. I made my living with that stuff for 7-8 years. Really versatile stuff.

-- I just got done cutting three boards and all four of them were too short. (true story)

View SCOTSMAN's profile


5849 posts in 3784 days

#14 posted 07-16-2011 08:11 PM

I would have thought this was totally unnecessary and a waste of money and time too. I like wood as it is not plastic looking wood.

-- excuse my typing as I have a form of parkinsons disease

View Steven H's profile

Steven H

1117 posts in 3259 days

#15 posted 07-16-2011 09:14 PM

Bondo is fine on wood for interior work, but for exterior it will crack like hel.
It is designed for metal use not wood.

Wood will flex more than metal.

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