3M Glaze

[Cato]

http://3mcollision.com/3m-acryl-marine-putty-white-05095.html

Any one have experience with this? I'm a regular user of their 2-part Bondo and am skeptical about non-catalyzed 1 parts. Most concerned about shrinking over time.

[Ace-Garageguy]

http://3mcollision.com/3m-acryl-marine-putty-white-05095.html

Any one have experience with this? I'm a regular user of their 2-part Bondo and am skeptical about non-catalyzed 1 parts. Most concerned about shrinking over time.

Sorry...I forgot to answer your PM. Any one-part product is basically just thick lacquer primer and it WILL shrink. It's OK for extremely fine scratch or pinhole repairs. but that's it. Any kind of high-fill or high-build situation isn't really a good idea.

All of them will do their most shrinking in the first 72 hours, but once re-coated with primer, they'll swell again as they soak up thinner. If you don't give them sufficient time for solvent re-evaporation, and you sand the primer flat fairly quickly, they will shrink again over time...even after having been painted, color-sanded and polished.

I have a decklid on a Chevelle that i rushed for a contest after I damaged it. The surfacers and one-part filler has shrunk to the point of needing re-sanding and polishing twice now in 4 years.

Edited July 2, 2016 by Ace-Garageguy

[Cato]

All of them will do their most shrinking in the first 72 hours, but once re-coated with primer, they'll swell again as they soak up thinner. If you don't give them sufficient time for solvent re-evaporation, and you sand the primer flat fairly quickly, they will shrink again over time...even after having been painted, color-sanded and polished.

Great point I never thought of - the absorption of solvent / thinners from subsequent coats, causing filler to swell. I'm well aware of not building-up thickness and only use fillers as intended. I was primarily interested in this one because of the white color, again used only for thin, small seams, cracks, pinholes. I stopped using Bondo 907 because of the color and shrinks.

Looks like good ol' Bondo 801 for everything.....

BTW, read of some guys using CA with either talc or flour(!) as a filler which they claim sands beautifully. I used it with baking soda on wood R/C aircraft decades ago...

 

[Muncie]

PPG, most other automotive paint companies, Squadron and Tamiya have a similar one part putty that is basically thick lacquer.  Bondo makes a consumer size package for home auto body repair,  - bad news - like a time bomb under the paint - Bill's got it correct.

With our hobby, it can also cause harm under the putty - as a lacquer based product, the solvents will also work their way into most of the primers that we use.  The solvents can make their way down to the plastic...  it's like putting a drop of lacquer on the plastic.  Art Anderson and Bill/Mr.Obsessive have educated us on the internal stresses in injection molded plastic.  The solvents in the putty can loosen some of those stresses and cause the plastic to start moving around - sink holes, warped lines, sanded off detail popping back up ...  yeh, don't ask me how I know...  this can show up before final paint, during polishing, and months later.

[Harry P.]

Never, ever, ever use any brand of "one part" putty. Ever. They all "dry" via evaporation of the solvent, and by definition, they shrink as they dry.

Always use a two-part product (putty + hardener). They don't "dry," they set via the chemical reaction between the two parts, and are much more stable over time than any one-part putty can ever be.

Bondo makes an excellent two-part putty than comes in a smallish tube (plus a tube of hardener), so no need to buy the big old cans of the stuff anymore. Their two-part "Professional" glazing and spot putty is just the right size for us car modelers. Just make sure the package includes the word "Professional," as they also sell a one-part putty that is sold in practically identical packaging. You don't want that one, you want the "Professional" one.

[Cato]

Just musing out loud here...

I'd have thought a company with the resources and chemical / engineering gravitas of 3M would, by now, have developed a 'miracle' one part auto filler. With all the attributes; quick drying, fine sanding and NO shrinking.

Of course paying for it would be the hard part...

 

[Harry P.]

I think it's physically/chemically impossible to produce a one-part filler that doesn't shrink, because every one-part filler is a combination of the filler itself, and the solvent that keeps it pliable in the tube. So as the filler dries via solvent evaporation, physically a portion of the filler disappears... hence, shrinking. No way around that that I can see.

[Ace-Garageguy]

Just musing out loud here...

I'd have thought a company with the resources and chemical / engineering gravitas of 3M would, by now, have developed a 'miracle' one part auto filler. With all the attributes; quick drying, fine sanding and NO shrinking.

Of course paying for it would be the hard part...

Bondo has a 1-part UV cure glazing putty. On my 'experimental' list.      

http://bondo.com/bondo-sun-activated-glazing-spot-putty-930.html#rMZDbYVwIBfbtZhA.97

 

[Longbox55]

I tried one of their UV cure "sun activated" putties about 20 years ago. Was not really impressed with it, never seemed to cure properly. However, I will concede that some of the issues with it may have been on my end, a combination of insufficient UV exposure to allow a full cure, my own (at the time) lack of experience with bodywork (this was on a 1:1 body panel), and definitely some severe impatience with allowing a full cure.

Knowing what I know now, and having worked with some other UV cure products (Bondic), if I were to try the UV cure putty again, I would use a UV lamp instead of relying on the sun.

[Harry P.]

Bondo has a 1-part UV cure glazing putty. On my 'experimental' list.      

http://bondo.com/bondo-sun-activated-glazing-spot-putty-930.html#rMZDbYVwIBfbtZhA.97

 

Well, technically, it's a two-part putty. The putty plus UV light (the "hardener") needed to cure it. Note they specifically point out that actual sunlight (UV rays)  are needed to cure it.

[Ace-Garageguy]

Well, technically, it's a two-part putty. The putty plus UV light (the "hardener") needed to cure it. Note they specifically point out that actual sunlight (UV rays)  are needed to cure it.

If you choose to interpret it that way, then yes, well. sort of.

But here's the thing.The MEKP added to traditional 2-part polyester products is only a CATALYST that kicks off an exothermic polymerization in the putty, and is not actually PART of the chemical combination itself.

UV initiates the polymerization of the UV-cure product, and as such, "sunlight" or ultra-violet light isn't part of the final chemical substance either.

The beauty of the UV-cure product is that it eliminates the measuring and mixing steps of using 2-part materials that some modelers apparently find to be problematic. 

And in the thicknesses modelers are going to be using, getting a full cure from the UV-activated stuff ought to be almost foolproof.

[Harry P.]

UV, schmoo vee... I'll stick with good old fashioned two-part catalyzed putty. Works every time.

[Snake45]

I use Sikkens glazing putty for some things, and over the years have worked out a routine with it that works for me.

1. Put on THIN coats. Let each one dry, sand, let the sanded surface dry 24 hours before the next coat. (If it needs more than 2 or 3 coats, I generally use something else.)

2. After the final shape has been achieved, let dry 24 hours, then soak generally with thin superglue (CA) and let that cure 24 hours.

3. Final sand the CA surface, prime and proceed as normal.

The CA seems to soak into the putty and really stabilize it. I've had nothing but good luck with this process. But generally for filler I use superglue, Loctitie Superglue Gel (ask for it by name), J-B Weld, epoxy, or sheet/strip/rod styrene, depending on the exact effect needed.

[Harry P.]

Why go through such a convoluted, time-consuming process when two-part putty sets up in about a minute? Why over-complicate such a simple process?

[Ace-Garageguy]

I pile on the Bondo Professional product. Never any futzing around waiting overnight to cure, no noticeable shrinking, almost no limit to how thick you can put the stuff on. 

ONLY time I'll use one-part is for tiny imperfections, for which it works a treat (Squadron Green shown here).

 

[Snake45]

Why go through such a convoluted, time-consuming process when two-part putty sets up in about a minute? Why over-complicate such a simple process?

I've had less than stellar luck with the 2-part products. Seems I never get the proportions right, and either they never cure, or they cure too fast and fall right off.

Have done okay with 2-parters that mix at 50-50, such as J-B Weld or the epoxy that comes in a double-barreled syringe thingie.  I can usually get that right.

Is there a good 2- part putty that mixes at 50-50?

(Besides which, I actually kinda enjoy doing things the old-school way in many cases.)

[Harry P.]

When I use the two-part Bondo, I just eyeball the mix. I probably use 1/10 the amount of hardener or less compared to the amount of putty, but the exact ratio isn't that critical. Visualize a golf ball and a pea... that's about the right ratio.

If you use too much hardener, the stuff will set up fast... maybe too fast for you to apply it and work it. Too little hardener and the stuff will set a lot slower... but it will eventually set. It just takes a few tries before you get the knack and can just eyeball the proportions. If the mix is a light pink color, that seems to be about right. Too red–you've used too much hardener; too white–you didn't use enough.

This is roughly that light pink color to aim for... but the exact ratio isn't super critical.

[Cato]

When I use the two-part Bondo, I just eyeball the mix. I probably use 1/10 the amount of hardener or less compared to the amount of putty, but the exact ratio isn't that critical. Visualize a golf ball and a pea... that's about the right ratio.

I

I generally go lighter than even that, to get a bit more working time. I've taken to putting down a thumbnail (literally) sized spot of filler, then stick the end of a 1/16 brass rod into the hardener tube (after kneading) and get some on the tip, then mix with that. Gives me the lightest of pinks which cures fine. Got tired of squeezing out a dot of hardener which drained all the fluid out of it, messing up the mix ratio. This way, I get just a dab of hardener with no 'soup'.

[Ace-Garageguy]

I generally go lighter than even that, to get a bit more working time. I've taken to putting down a thumbnail (literally) sized spot of filler, then stick the end of a 1/16 brass rod into the hardener tube (after kneading) and get some on the tip, then mix with that. Gives me the lightest of pinks which cures fine. Got tired of squeezing out a dot of hardener which drained all the fluid out of it, messing up the mix ratio. This way, I get just a dab of hardener with no 'soup'.

Excellent, and much the same way I use it. The separated "soup" is the actual MEKP component of the catalyst, and it's imperative the tube is thoroughly kneaded prior to dipping out your material, as you note.

There actually IS an ideal mix ratio when dealing with this species of polyesters, which in this case is about 1%-1.5% catalyst to resin. Because of the thickeners and inert components, it's difficult to get this ratio consistently in small quantities by measuring...which is why the manufacturers added the colorant to the catalysts.

"Light pink" is without doubt the post-mixing target to shoot for. (And there IS a lower threshold of catalyst below which the material will NEVER cure properly). 

 

Edited July 3, 2016 by Ace-Garageguy

[Harry P.]

There actually IS an ideal mix ratio when dealing with this species of polyesters...

Yes, technically I'm sure there is an "ideal" ratio. But I've never had a problem just eyeballing it, and I'm sure I don't get it exactly right every time. But it works for me every time, so obviously there is a range that the stuff will work within. That "salmon" color is what I shoot for. Works every time.

[Ace-Garageguy]

Yes, technically I'm sure there is an "ideal" ratio. But I've never had a problem just eyeballing it, and I'm sure I don't get it exactly right every time. But it works for me every time, so obviously there is a range that the stuff will work within. That "salmon" color is what I shoot for. Works every time.

Yes, and you have to remember the stuff was invented for and is made for easy body-shop use, where the typical practitioner wouldn't measure anything even if it WAS necessary. It is nothing more than a fine-grained bondo, chemically identical. The original "Bondo" catalyzed polyester filler introduced in 1955 was made to get around the high degree of skill required to work with the lead fillers previously used.

There is a wide latitude of mix ratios that will "work" just fine, specifically because it's aimed at 1:1 users who are, let's say, less than precise in their approach to life.

But the problems people have with the stuff come from failure to mix the catalyst (and resin if it settles) properly PRIOR TO MIXING THEM TOGETHER, failure to mix the combined components properly, and failure to stay within the mix-ratios that will give acceptable performance

A little practice is all anyone needs to get consistent results.

[Cato]

Yes, and you have to remember the stuff was invented for and is made for easy body-shop use, where the typical practitioner wouldn't measure anything even if it WAS necessary. It is nothing more than a fine-grained bondo, chemically identical. The original "Bondo" catalyzed polyester filler introduced in 1955 was made to get around the high degree of skill required to work with the lead fillers previously used.

Bill, in the small quantities modelers use, what's the shelf life of 801? And how does it act when it's past its life?

[Ace-Garageguy]

Bill, in the small quantities modelers use, what's the shelf life of 801? And how does it act when it's past its life?

The catalyst will usually last for several years. It will separate, but can be readily mixed again into a nice red homogeneous liquid, as you note. When it remains 'grainy' after mixing, it's toast. The small plastic tubes often crack and split before the material goes bad.

The filler itself is usually good for anywhere from 6 months to a couple of years. A lot depends on how long it was on the shelf before you bought it, how it's stored, and what packaging it's in.

I have some 801 in the metal tube that's two years + and still OK if I stir it with a stick prior to use. (The clear 'resin' component will come out of suspension on almost all of the inert-material-filled polyester products), but the same product in the larger plastic container (391) has dried out and become too stiff to use over the same 2-year period.

In general, if you can still stir the clear component of the filler back into a nice creamy gray paste, it's good to use. If it's stiff and hard and lumpy, forget it.

Some VERY old catalysts I've had have failed to initiate polymerization, but I don't think you'll ever face this particular issue.

 

[Cato]

Thanks Bill. Great discussion here by all.