Author Topic: Using zinc stearate (sp)? (Read 6546 times)

Rob Killick · « **on:** March 30, 2015, 12:49:11 PM »

Hi ,

I want to use zinc stearate , as a filler on my model(s). I tried it on my model's elevator and horizontal stab and found after drying , it leaves a texture , somewhat like (as close as i can describe) parafin wax .
I've mixed about one tablespoon of zinc to one half pint of dobe , thinned 60% thinner to 40% dope . it has the consistency of milk . It seems to do a great job of filling , but I'm worried that when I put down the dop finish coats , it won't adhere properly .
Anyone have any info on doing this type of fill coat correctly ?
Thanks in advance ,

Rob K.

Allan Perret · « **Reply #1 on:** March 30, 2015, 01:09:20 PM »

Your mixture sounds about right, not sure what you mean by the paraffin wax texture. The texture should not matter because it needs to be sanded flat and smooth with 320 or finer before application of finish coats.

Rob Killick · « **Reply #2 on:** March 30, 2015, 06:59:30 PM »

Thanks Alan ,

I'll continue on ...
Thanks for the help .

Rob K.

Tim Wescott · « **Reply #3 on:** March 30, 2015, 07:03:27 PM »

If you lay on a lot of Sig sanding sealer before sanding it you get a similar texture.

Remember that you want to sand most of the sealer off -- "sealer" is a misnomer, since you're really using it as primer.

wwwarbird · « **Reply #4 on:** March 30, 2015, 08:46:30 PM »

Please keep us posted on how this goes for you Rob. I've got some that I've never used because I've had the same concerns about adhesion when pulling masking materials later in the finishing process.

MikeyPratt · « **Reply #5 on:** March 31, 2015, 08:42:49 AM »

Quote from: Rob Killick on March 30, 2015, 12:49:11 PM

Hi ,

I want to use zinc stearate , as a filler on my model(s). I tried it on my model's elevator and horizontal stab and found after drying , it leaves a texture , somewhat like (as close as i can describe) parafin wax .
I've mixed about one tablespoon of zinc to one half pint of dobe , thinned 60% thinner to 40% dope . it has the consistency of milk . It seems to do a great job of filling , but I'm worried that when I put down the dop finish coats , it won't adhere properly .
Anyone have any info on doing this type of fill coat correctly ?
Thanks in advance ,

Rob K.

Hi Rob,
This is great stuff when mixed properly (2 table spoons per quart). I brush on two coats on wood parts (spray on open bay covering) and let dry for a few days. Then wet sand with 400 grit sandpaper and a little water. While you are sanding the filler, candle the model by holding it up to a light and bouncing the light of the part (or wings) making sure that you do not sand through into the underlying covering ( if you do sand through, reapply more primer).

This will give you a very smooth and properly filled surface. When you are finished sanding the primer, spray a coat of clear (with a small amount of white added to the clear) over the primer to seal it. By adding the clear coat over the primer it will show imperfections that may have not been seen before (fix then at this time).

Take your time and enjoy the process, don't rush it.

Later,
Mikey

bob whitney · « **Reply #6 on:** March 31, 2015, 12:21:06 PM »

OK this is a new one to me, What is it and where do u get it

wwwarbird · « **Reply #7 on:** March 31, 2015, 06:38:15 PM »

Quote from: MikeyPratt on March 31, 2015, 08:42:49 AM

This is great stuff when mixed properly (2 table spoons per quart).

Mikey,

Are you figuring 2 table spoons to your pre-thinned clear, or to straight clear before thinning?

MikeyPratt · « **Reply #8 on:** March 31, 2015, 06:40:19 PM »

Quote from: wwwarbird on March 30, 2015, 08:46:30 PM

Please keep us posted on how this goes for you Rob. I've got some that I've never used because I've had the same concerns about adhesion when pulling masking materials later in the finishing process.

Hi Wayne,
That can happen when you mix too much in the clear. Two level teaspoons only per quart of clear dope. That happened on my Super Aries. Also, I didn't seal it down with clear when the sanding was completed. Some guys like to add Polar Gray to the coats on top of the primer. I'm not sure if it makes any difference which color you choose. I like the white to build up the white base and takes less white for complete coverage.

Later,
L
Mikey

MikeyPratt · « **Reply #9 on:** March 31, 2015, 06:42:22 PM »

Quote from: wwwarbird on March 31, 2015, 06:38:15 PM

Mikey,

Are you figuring 2 table spoons to your pre-thinned clear, or to straight clear before thinning?

Hi Wayne,
Straight clear not thinned. Then thin for spraying.

Mikey

wwwarbird · « **Reply #10 on:** March 31, 2015, 09:29:13 PM »

Thanks for the info Mike. I've had a container of the Randy Smith stuff for a long time that I've never opened, maybe I'll give it a whirl on the next project.

Massimo Rimoldi · « **Reply #11 on:** April 01, 2015, 12:24:04 AM »

Quote from: wwwarbird on March 30, 2015, 08:46:30 PM

Please keep us posted on how this goes for you Rob. I've got some that I've never used because I've had the same concerns about adhesion when pulling masking materials later in the finishing process.

Hello everyone,
I apologize for my bad English but I hope you understand the same.

My company's business is in the field of paints for industrial use, then fit I know very well the problem.
The Zinc Stearate is widely used as a filler in primers for wood, then use for our purposes is right.
In addition to filling, Zinc Stearate gives smoothness during sanding action based on its self-lubricating properties.
The amount of Zinc Stearate that are mentioned in the previous posts seem absolutely correct for the purpose.
The only advice I can add to prevent delamination of subsequent layers, is to eliminate the traces of sanding dust with the aid of a damp cloth.
Better yet with the use of a specific solvent for the cleaning of surfaces before painting.

Hope this helps,

Massimo.

Massimo Rimoldi · « **Reply #12 on:** April 01, 2015, 08:05:01 AM »

Quote from: Ty Marcucci on April 01, 2015, 07:38:20 AM

It seems Massimo, Mike and I are saying the same thing. I didn't mention I wipe the dust with a damp paper towel. I just assumed all knew this. Mikes ratio and mine are the same, I just mix smaller batches as this stuff goes a long way. Once you try this stuff, you will never use talc again.

Good morning Mr. Marcucci,
I agree with you that after this stuff, talc is obsolete ....
I return to the models after many years and I'm finding a lot of news on the internet.
I read somewhere that is also used corn starch (the specific weight should be less than stearate).
She has some experience?

Regards, Massimo.

Rob Killick · « **Reply #13 on:** April 01, 2015, 09:57:29 PM »

Wow !

Didn't think I'd get such great responses

I cut back my mixture (as Ty recommended) and it came of nicely , after waiting 24 hours .
I forgot to mention , that I'm brushing it on over silkspan .
Thanks to everyone for a gvery helpful response to my question .

Rob K.

Brian Carolan · « **Reply #14 on:** April 02, 2015, 10:43:40 AM »

Hi,
I'm new to here - A nice forum with good info.
Anyway this topic is of interest for a project that got stalled some by health issues last year ; http://www.rcuniverse.com/forum/rc-pattern-flying-101/11585770-wing-section-new-bipe.html
Hope it's ok to post the link.
I'm a little confused re the mix ratios above.
A 'supplier' ( not to mention names) of zinc stearate based filler advised me to use 4 heaped table spoons / quart of raw dope and then thin. I am 2 weeks from trying it.
I have 1400sq/in's of wing and tails, rudder etc to do. That's 3500 sq's of surface area - so I want to get it right and as light as possible.

I got the ZS from a lab chemical supplier here in Ireland for €25 for a Kg - made by Aldrich Germany.

Brian

Massimo Rimoldi · « **Reply #15 on:** April 02, 2015, 11:21:40 AM »

Quote from: Brian Carolan on April 02, 2015, 10:43:40 AM

Hi,
I'm new to here - A nice forum with good info.
Anyway this topic is of interest for a project that got stalled some by health issues last year ; http://www.rcuniverse.com/forum/rc-pattern-flying-101/11585770-wing-section-new-bipe.html
Hope it's ok to post the link.
I'm a little confused re the mix ratios above.
A 'supplier' ( not to mention names) of zinc stearate based filler advised me to use 4 heaped table spoons / quart of raw dope and then thin. I am 2 weeks from trying it.

Good Morning,
as for the majority of things, also in this field does not exist the unique and irreplaceable recipe.
The amount of ZS depends on:
1) Percent of the dryness of the dope before dilution
2) capabilities filler that we want to get the mix
The same result is obtained without the use of ZS, in this case are required more coats and sanding is considerably more difficult.
The important thing (as always) is not overdo.

Regards, Massimo.

Dennis Saydak · « **Reply #16 on:** April 02, 2015, 04:44:13 PM »

It's GREAT stuff! Here's what Randy says:

"Many use it in dope, like you would talc or corn starch, I mix up a qt jar with 4 tablespoons of ZS filler, it is much lighter than talc or starch and sands way better, I thin just enough to brush it out on bad places but mainly I shoot it thru a gun at 100% thinner added, after it dries, I then look for bad spots, i brush it on thick over "only" the bad spots, then sand it off and spray again...repeat until smooth. I also put about 4 drops of black in the mix to get a light grey, this shows up all the flaws. It goes over not under paper, It is not a gap filler or meant to fill big flaws or voids, do that with light weight model magic or some other filler.

Randy"

Rob Killick · « **Reply #17 on:** April 02, 2015, 07:53:22 PM »

By the way ...

I get my zinc stearate from my local pharmacy . Comes in a two quart (approx) container.
I can't remember the price , but cheap.

Rob K.

Howard Rush · « **Reply #18 on:** April 06, 2015, 12:49:15 PM »

I used some of Randy's to fix a problem on my last dog. I had a seam in my superlight 1/16" LE sheeting that formed a ridge that got worse with sanding. I blew on some zinc stearate (bummed from Mike Haverly) mixed with Randolph dope, probably in the recommended proportions. A coat or two filled in either side of the ridge sufficiently that light sanding made the ridge go completely away. The result was transparent. There was no adhesion problem, and the ridge hasn't come back. It's great stuff.

Randy Powell · « **Reply #19 on:** April 06, 2015, 08:13:10 PM »

Howard, Did you use the medically cleared stuff?

Howard Rush · « **Reply #20 on:** April 06, 2015, 09:36:21 PM »

You can buy recreational zinc stearate in Washington now.