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View Full Version : PC - Curious about your Double Coat Methods



rototerrier
02-04-2017, 07:14 AM
First of all, I don't actually need 2 coats. One coat in my 45acp works fine, but what I'm really trying to do is get the best looking coverage. I've got a project I'm working on where the bullets need to look really good.

I use a rcbs tumbler and every single color comes out looking perfect with one coat with the exception of smokes white.

They go in the oven looking flawless and come out splotchy. I've done a few experiments with double coating with great results, but I'm curious how everyone else does it.

I read where it was suggested the first coat be only partially cured. I tried that and it didn't work.

I brought them up to just the point the coating start to "melt" or whatever you call the transition from dry powder to the wet state.

I pulled them out and immediately put them under a fan to cool. Then threw them back in the tumber for 5 minutes and hardly any powder would stick to them. It's as if that partially cured coating had anti static properties or something.

The only method of double coating that I've gotten to work is to fully cure the first coat before applying the second. When I do that, I get the same awesome coverage with both coats.

They also pass the smash test.

But, I'm wondering, is it really all that important to just partially cure the first coat and if so, what did I do wrong? Why won't any powder stick to "my" partially cured coat? Did I over partial cure or under partial cure? Is ensuring both coats "mix" or "bond" together critical? Seems to me just layering multiple fully cured coats should be sufficient.

Just wanting to satisfy my curiosity here about why my partial cures are so impervious to secondary coats.

popper
02-04-2017, 12:33 PM
The manufacturers recommend just a single coat. Where extra coating thickness is needed for durability, single heavy coat may orange-peel/sag. They want both layers to cross-link vs 2 separate non-linked layers, for a stronger, fully weatherproof coating. Unless you are building up the size of a boolit it probably doesn't make a difference. ESPC is the norm.

rototerrier
02-04-2017, 01:47 PM
The manufacturers recommend just a single coat. Where extra coating thickness is needed for durability, single heavy coat may orange-peel/sag. They want both layers to cross-link vs 2 separate non-linked layers, for a stronger, fully weatherproof coating. Unless you are building up the size of a boolit it probably doesn't make a difference. ESPC is the norm.

But, I'm wondering, is it really all that important to just partially cure the first coat and if so, what did I do wrong? Why won't any powder stick to "my" partially cured coat? Did I over partial cure or under partial cure? Is ensuring both coats "mix" or "bond" together critical? Seems to me just layering multiple fully cured coats should be sufficient.

Really just looking to see how in the world people do 2 coats with "cross-link"? It seemed like it would be simple until I couldn't get powder to stick to the uncured layer.

runfiverun
02-04-2017, 02:14 PM
the second coat usually don't stick to the first coat because it's too slick.
when I tried 2 coats I got the first one 'wet' then took them out.
I let them cool down but not to room temp just to about 140-150 or so then dumped them in the powder again.
they took more powder oh boy did they take more powder.
then back in the oven for a full cook.
when they got a full cook-off the 2 coats become 1 full coat from the curing process.

prickett
02-05-2017, 07:22 PM
I double coat with HF paint and get great results. I fully cook the first - somewhat spotty coat (400+ degrees) for 30 minutes. I size, then coat again. This time the paint adheres fully. After cooking for 30 more minutes, the coating is smooth, fully covered, and durable.

bkbville
02-06-2017, 03:02 PM
The only time I didn't fully cook the first coat was when i forgot to set the oven temp and had run time for 30min at 300F - when I went to size them I could see they hadn't cured, figured it out, and added a second coat at the correct temp. They were fine after that. Now I make sure to check the temp.

By choice though - I fully cook both coats, though I admit I see no difference in either method.

The synthetic polymer surface of the first coat seems to provides improved static attraction for a more even and complete second coat - at least for shake and bake. (Don't know if it's any better with ESPC)

Makes me wonder if there is a coating of some sort that would improve the static attraction of the raw boolits without a second coat...

rototerrier
02-06-2017, 03:30 PM
Well, I've thought this through and figure it really doesn't matter how the second coat goes on.

Since the first coat is sufficient, and the second coat in my case is purely for cosmetics, then I guess it doesn't matter that I fully cure the first before applying the second.

Even if the second coat failed, the first is sufficient.

I usually only single coat and haven't had any issues. This whole thing came up because of some white powder I got from Smokes that just doesn't cover well. It leaves a lot of speckles from the dry tumbling. It looks fully covered until it bakes, and then it exposes the spots. It's crazy stuff. A second coat clears all that up and they look amazing.

The particular boolits are for other people, and I want them to present well. For myself, I really don't care that they are splotchy.

All other colors, particularly darker colors, don't suffer from this issue.

Here they are with the double coated whites next to single coated red and blue. You can kinda see light splotchyness in the red and blue, but it just doesn't show up as well as it did on the whites without the double coating. I don't have any single coated whites for comparison...but they do look pretty rough.

187399

prickett
02-07-2017, 12:45 AM
I double coat for two reasons

1 - The first coat (using HF paint) doesn't cover but 75% of so
2 - I resize in between coats. I'm using a TL mould and the thin ridges have a tendency to shear off, so the second coat recoats the bare spots. Also, any variances in the size of the boolit (i.e. falling out oversized) tends to also result in lead being shorn off.