Author Topic: Minwax Polycrylic and talc or zinc sterate? (Read 6883 times)

Bill Little · « **on:** February 14, 2012, 04:50:59 PM »

Hi All,

I vaguely remember reading that some people have used the water based MinWax Polycrylic mixed with talc or zinc sterate as a filler under Rustoleum, etc..

If you have used it, how did it work for you? And about what is the ratio you use?

Thanks!
BIG Bear
RNMM/AMM

Tim Wescott · « **Reply #1 on:** February 14, 2012, 11:16:08 PM »

I've used it with talc, and it works nicely.

I'm currently experimenting with acrylic indoor primer, which is not only easy to sand, but doesn't settle out the way that talc does and is really, strongly white, so I can see where it is (I have a real problem with sanding through my sealer coats). I've only done this on one plane, and I did it over Minwax Polycrylic, and I did have adhesion problems to the Polycrylic -- but that's my fault for putting too many innovations in a row into one paint job.

I know that Allen Brickhaus recommends Minwax polycrylic with fiberglass as a base, then spackling compound (thinned, if I recall correctly, with water), then spray-bomb. He's got an article called "finishing the Oriental" in some 2010 issue of Flying Models -- but I cannot remember which month.

Balsa Butcher · « **Reply #2 on:** February 14, 2012, 11:43:49 PM »

Does Alan recommend actual fiberglass or just Z-Poxy fiberglass resin as a base? I was under the impression that you could initially treat the wood with polycrylic or a fiberglass resin but didn't need both.

Tim Wescott · « **Reply #3 on:** February 15, 2012, 12:31:27 AM »

He was advocating using Polycrylic to stick 1/2 oz fiberglass cloth onto the wood.

Balsa Butcher · « **Reply #4 on:** February 15, 2012, 06:18:44 PM »

Got it...thanks. I have always used a Z-Poxy type product for that but I like the water-solubility of polycrylic and can't argue with the results Mr. Brickaus gets.

Mike Keville · « **Reply #5 on:** February 15, 2012, 07:18:41 PM »

Although not a Stunt design, Minwax Polycrylic (Satin finish) was used to seal the raw balsa and 1/64" ply wing covering on this 1cc profile scale A-26. Five coats, sanded between each with 400 grit, followed by Rustoleum auto primer. Color coats were Rustoleum "American Accents" satin...all topped with Ace satin polyurethane. All of this gave a rather nice light finish.

Allan Perret · « **Reply #6 on:** February 16, 2012, 07:30:26 AM »

Quote from: Tim Wescott on February 14, 2012, 11:16:08 PM

He's got an article called "finishing the Oriental" in some 2010 issue of Flying Models -- but I cannot remember which month.

It was "Finishing the Olympus" in Flying Models, May 2010.

Steve Fitton · « **Reply #7 on:** February 16, 2012, 07:43:31 AM »

Personally I would not do that unless it was a disposable plane. The polycrylic finish on my old time machine turned to mush after 150 flights.

Allan Perret · « **Reply #8 on:** February 16, 2012, 07:58:11 AM »

Quote from: Steve Fitton on February 16, 2012, 07:43:31 AM

The polycrylic finish on my old time machine turned to mush after 150 flights.

The whole plane or just where subjected to fuel ? What was your final topcoat on the Time Machine ?
Brickhaus' method uses the water based polycrylic only as a base; with Rustoleum aerosol for topcoats, and also 2-part auto clear coat for the Olympus.

Bootlegger · « **Reply #9 on:** February 16, 2012, 08:41:26 AM »

Hey Allen, I got some from Home Depot in a 1Qt can with a black label, and painted a handle with three coats.
From what I understand this stuff is fuel proof, but not the water base.
If I remember the label said it is a Lacquer base.
Hope that this helps...

Tim Wescott · « **Reply #10 on:** February 16, 2012, 10:16:06 AM »

Polycrylic turns to mush when you put fuel on it, but Rustoleum Gloss Protective Enamel (which is what I have experience with -- others are supposed to work as well) seems to hold up well to fuel.

My first plane that was painted with Polycrylic/Rustoleum turned to splinters after about 100-200 flights, but I don't think it was the paint reacting with the fuel that did it.

Steve Fitton · « **Reply #11 on:** February 16, 2012, 10:35:08 AM »

On my Time Machine the polycrylic/silkspan was covered with lustrekote primer, color and clear. After exposure to sun and hot weather the lustrekote checked and crazed, letting in the oil residue and trashing the polycrylic. After refinishing the plane with .5 oz glass and zpoxy, the lustrkote lasted much longer (about 500 flights) before crazing, and then the fuel didn't penetrate the z poxy/glass so the plane didn't oil soak and turn to mush again.

phil c · « **Reply #12 on:** February 16, 2012, 04:16:53 PM »

If you are filling wood with a polycrylic varnish save a lot of sanding time. Put 3-4 coats on, one after the other. Then sand once to take most of it off and get a smooth base. Sanding each coat doesn't produce a smoother finish because the first couple coats don't fill in completely, so additional coats are needed anyway.

Fuel proof versions of polycrylic, if you can find them, are Varathane Gloss, and Carver-Tripp.

Bill Little · « **Reply #13 on:** March 04, 2012, 06:45:12 PM »

It is my understanding that Minwax urethane in the black can is somewhat hot fuel resistant. The water based in the blue can, however, is no where near fuel resistant.

Just looking at alternatives to filling the grain............... especially when using a Rustoleum top coat.

BIG Bear
RNMM/AMM

Allan Perret · « **Reply #14 on:** March 06, 2012, 01:39:04 PM »

Quote from: Bill Little on March 04, 2012, 06:45:12 PM

It is my understanding that Minwax urethane in the black can is somewhat hot fuel resistant.

The Minwax with black label is not a urethane, its what they call a "Brushing Lacquer".

Bill Little · « **Reply #15 on:** March 06, 2012, 02:23:39 PM »

Quote from: Allan Perret on March 06, 2012, 01:39:04 PM

The Minwax with black label is not a urethane, its what they call a "Brushing Lacquer".

Thanks, Allen. I was going on the black spray can I have from Minwax. I'll have to check it again! LOL!!

BIG Bear
RNMM/AMM

Dennis Adamisin · « **Reply #16 on:** March 06, 2012, 04:50:55 PM »

I tried using water based poly (minwax I think) on a RC sailplane, the water base made the balsa puff up rough as a cobb. - how do you guys keep that from happening?

Bill Little · « **Reply #17 on:** March 06, 2012, 05:05:07 PM »

Quote from: Dennis Adamisin on March 06, 2012, 04:50:55 PM

I tried using water based poly (minwax I think) on a RC sailplane, the water base made the balsa puff up rough as a cobb. - how do you guys keep that from happening?

HI Bro Denny!

So far, the Polycrylic has not raised the grain any more than, if as much as, a coat of dope. I don't know why.............

Bill

Brett Buck · « **Reply #18 on:** March 07, 2012, 12:47:31 AM »

Quote from: Dennis Adamisin on March 06, 2012, 04:50:55 PM

I tried using water based poly (minwax I think) on a RC sailplane, the water base made the balsa puff up rough as a cobb. - how do you guys keep that from happening?

I have used it on several different projects (balsa and hardwood) and that's about what it did for me, too. The only satisfactory results I have gotten was to put on multiple coats and waiting A LONG TIME between them, without attempting to sand anything between. Sand too much early on, and all you get is spots where it seals and spots where it doesn't and the unsealed spots just get the grain raised again.

Once you get it on there in a continuous coat, it's very tough and hard as a rock. My most successful job has been my toolbox and it has gotten bashed around for 10 years or so and while it's a little scuffed up, the finish is essentially intact.

Brett

Dennis Adamisin · « **Reply #19 on:** March 08, 2012, 02:54:07 PM »

Quote from: Bill Little on March 06, 2012, 05:05:07 PM

HI Bro Denny!

So far, the Polycrylic has not raised the grain any more than, if as much as, a coat of dope. I don't know why.............

Bill

Coach:
You know what happens when you get a drop of water on some good balsa - and it puffs up where the drop was? Imagine the ENTIRE surface puffing up like that. - as occurred to me. I did it again with a wing sheeted with Poplar veneer (very tight grain, & harder than balsa) and did a coat a day - worked better.

Tim Wescott · « **Reply #20 on:** March 08, 2012, 03:06:08 PM »

Quote from: Brett Buck on March 07, 2012, 12:47:31 AM

I have used it on several different projects (balsa and hardwood) and that's about what it did for me, too. The only satisfactory results I have gotten was to put on multiple coats and waiting A LONG TIME between them, without attempting to sand anything between. Sand too much early on, and all you get is spots where it seals and spots where it doesn't and the unsealed spots just get the grain raised again.

The key is to not sand through the base coat. That's why I started using acrylic primer -- it's white with good coverage so I can see when I'm about to break through -- then I know it's time to stop sanding and start painting again. It sands easier than Polycrylic, too. But don't blame me if you try it and it doesn't work -- my first test article only has four or five flights on it, so I can't say much about durability yet.

Come to think of it, this might be part of the reason why Master Brickhaus's method is successful: if you sand through the filler coat you're into fiberglass, not wood, so you won't puff it up when you recoat and start over on that patch.

Quote

Once you get it on there in a continuous coat, it's very tough and hard as a rock. My most successful job has been my toolbox and it has gotten bashed around for 10 years or so and while it's a little scuffed up, the finish is essentially intact.

Except that it isn't fuel proof. I painted my first Fancher-style handle with Polycrylic and it was great until I started using it -- then the fuel on my hands and the moisture in the grass made the dang stuff get sticky. Oil-based varnish is fuel proof, looks just as good, but is reputed to yellow. On bare wood that yellowing is an "attractive patina", so that's what I use.

Motorman · « **Reply #21 on:** November 02, 2015, 05:39:58 PM »

Quote from: Dennis Adamisin on March 06, 2012, 04:50:55 PM

I tried using water based poly (minwax I think) on a RC sailplane, the water base made the balsa puff up rough as a cobb. - how do you guys keep that from happening?

First 2 coats on bare balsa are Sig nitrate dope thinned 50/50. Good adhesion and protects the wood from water based polycrylic. A trick taught to me by Bill Mazzoni.

MM

EddyR · « **Reply #22 on:** November 05, 2015, 05:25:49 AM »

My test showed it to be fuel proof but not exhaust proof. The exhaust softens it. I was trying it as a top coat.
Ed

louie klein · « **Reply #23 on:** November 05, 2015, 08:27:33 AM »

Hi guys, I use the whole poly,rustolium,clear process on 4 planes with no problem. I do let it sit for a while before flying. No problems yet, But I do wipe the plane down after each flight so the gas does not "sit" on the paint just in case. The last plane I finished, a Brodak Accentor, I did leave in the truck cab in the hot summer days to let cure and it seamed to work well. Good luck, Louie

Avaiojet · « **Reply #24 on:** November 05, 2015, 01:15:19 PM »

There's Minwax Polycrylic, on the fuselage of this model. Applied over a few coats of clear dope used to attach the silk. Sanded the dope lightly before applying the Minwax. Primer followed the Minwax.

Charles

Avaiojet · « **Reply #25 on:** November 16, 2015, 10:24:52 PM »

Here's the finished model.

RC Storick · « **Reply #26 on:** November 20, 2015, 10:19:34 PM »

Quick way I use to finish in the 1990 was Zpoxy painted on and carded off then dry with paper towel to get everything off. Let dry over night then dc-540 and paint. I might do another like that soon to see what difference in weight there is.