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View Full Version : Coating cracking and flaking. Whats the cause.



A pause for the COZ
01-09-2014, 04:20 PM
Did my 1st batch last night. They look great. I dont think it adhered to well to the bullet.

Coating seems brittle where you take it off from the pan and after running them through the sizer it looks like its cracking with little nibs breaking off.

What do you think I did wrong?
Used a HF gun with HF red.

Put on to thick?
Cooked too long or not long enough?
Temp too hot or too cold?
I tried to get a good image, but my camera is not cooperating with those right now.

http://i33.photobucket.com/albums/d66/Kelly2215/101_9115_zps32a9bb60.jpg

Here is what the flaking looks like. These are just flashing from removal from the pan. But at least you can kinda see.

http://i33.photobucket.com/albums/d66/Kelly2215/101_9116_zps1a34b5da.jpg

http://i33.photobucket.com/albums/d66/Kelly2215/101_9112_zpsb0cd7752.jpg

http://i33.photobucket.com/albums/d66/Kelly2215/101_9109_zpsd168acd8.jpg

KYShooter73
01-09-2014, 04:48 PM
Its normal for the sizer to take off the little excess flash around the base. If it is flaking off elsewhere, I would guess your boolits are not clean and need to be rinsed in some acetone before you spray.

JASON4X4
01-09-2014, 04:53 PM
smash one with a hammer and the coating should not come off. I soak all mine in acetone then stand them up on the tray and let them air dry before I spray them with the powder.

bangerjim
01-09-2014, 05:07 PM
Hammer test......tells all! I always check one from each batch........just to be sure.

You could have grease or oil from your fingers on them.

I am very aware of what the HF bottles say on bake time. But I have found that you only need 10 minutes at 400F (preheated to 400......VERY important!) to get a perfect bake in any HF color.

I prefer the black but I have used the red and find it tends to coat thick.....waaaaay too thick as opposed to the black. Back off on your spray time and powder usage to get a thinner coat. A thick coat will crack at the base when you pick them up. That flash comes off in the size die and normally will not hurt anything, especially with GC's.

400 is the perfect temp. Get a good thermometer to check your oven. Most inexpensive ovens do not have a good temp control. I use a HF IR thermometer to shoot the boolits. Once you get a good idea of the oven "profile" of temp, you do not need to check it and will know where to set your dial.

I think baking 20-25 minutes as some say the do is just a big waste of time and electricity! I get perfect, hard, no crack, no leading coatings at 400 for 10 min as stated above.

bangerjim

freebullet
01-09-2014, 07:59 PM
Use nonstick foil under them. Or spray the plate with silicone. Possibly cooked to long, could dry them out too much. They look nice though.

A pause for the COZ
01-10-2014, 01:16 AM
Thanks guys. I did use Acetone 1st and wore powder free rubber gloves. Dried them with compressed air and let then sit over night on the tray before spraying. I did use a thermometer in the oven.
I did preheat the oven to 400 deg. The dial on the oven was set at 450 to get to 400.
I did notice that after I opened the door and stuck the tray in. The temp dropped to 350 deg. It stayed at 350 deg for about 5 minutes then rose back to 400. I cooked them for a total of 20 minutes as per the instructions.

I will try the hammer test. The only place I see cracking is just above the gas check where the flashing from the nonstick foil.
Maybe they are fine and I am just being anal. 1st time so I dont know what good is or what bad is.

bangerjim
01-10-2014, 12:34 PM
Use nonstick foil under them. Or spray the plate with silicone. Possibly cooked to long, could dry them out too much. They look nice though.

I have found that ANYTHING under the base of the boolit will wick up on the sides and keep the powder from sticking. That is why NS foil works. You can only get 2-3 bakes from a piece, depending on how thick your are spraying. You start getting that heavy flash at the bottom and the foil starts tearing.

Again 400F at 10 min is all it takes! (pre-heat oven)

banger

MrWolf
01-12-2014, 01:36 PM
I am still waiting on my mould - bought the HF pc gun and paint, and had a thought. Since for my 45 I will not need a gc, why not use a nut and bolt on the trays? Bolt only goes through tray enough for nut to adhere. After several uses, either hit with wire wheel or just flip the nut over or replace. Also thought of making a small top tray using something like a carpet tack strip. Something thin with just a point set up above every nut so it could be placed on top of the tray for easier transfer to the oven with no tipping. The tray could have a post on each corner for easy alignment. I was also looking at allpowderpaints.com for future colors as they seem reasonable with only $6.99 shipping to U.S.. You guys have me thinking about this WAY to much :Fire:

bangerjim
01-12-2014, 06:00 PM
I am still waiting on my mould - bought the HF pc gun and paint, and had a thought. Since for my 45 I will not need a gc, why not use a nut and bolt on the trays? Bolt only goes through tray enough for nut to adhere. After several uses, either hit with wire wheel or just flip the nut over or replace. Also thought of making a small top tray using something like a carpet tack strip. Something thin with just a point set up above every nut so it could be placed on top of the tray for easier transfer to the oven with no tipping. The tray could have a post on each corner for easy alignment. I was also looking at allpowderpaints.com for future colors as they seem reasonable with only $6.99 shipping to U.S.. You guys have me thinking about this WAY to much :Fire:

Any method that involves wire brushing or cleaning is too time consuming. That is why we use NON-STICK foil.....cheap, easy to find, and easy to change out!

Press it over washers, nuts, bumps......whatever you want to use for a tray base. But the foil os the ONLY way to go.

One thing to keep in mind that many seem to be overlook is when using a convection (fan) oven, which is the ONLY kind that really works for what we are doing, you must allow for air circulation around the back and sides of the trays. Making solid trays will defeat the entire purpose of convection air circulation. Without convection, you will get melted boolits above the coils and cold spots around the edges. Not what you want. Standard ovens do not work well due to hot and cold spots. They work OK for baking food stuff as the pans and dishes act as heat regulators and spread out the uneven temps with their mass. Our little boolits are totally different and have virtually zero mass.

When designing/building your "dream" rack......you must allow for that air circulation and cannot use solid plates that span the entire oven cavity.

Just a head's up......from experience!!!!!!!!!

Once you actually get your stuff and really start coating, you will find out what works and does not. Read the stickies........as MANY things have been tried.....very few actually work!

bangerjim

MrWolf
01-12-2014, 09:39 PM
After awhile all this information starts to blur and I have read the stickies and posts. I can't find it but I thought Beagle used the nut so the coating went to the base and made a nice ring on the base. I could not remember if he used the non-stick foil to do it. I can see the picture of the boolit in his palm but can't find it. Good point about leaving room for air circulation - don't recall seeing that point made.

bangerjim
01-13-2014, 01:09 AM
We ALL use NS foil! Standard foil is a total mess. If you do NOT use foil, you coat your base plate and have to grind/scrape/brush the very hard PC off!

Many press the foil over nuts, bolts, washers, whatever to elevate the boolits and to give a hole for GC areas to go in, especially for 223's and 30's so they will not fall over.

I use nothing to elevate for 9/38/40/45 cal's. I just change the foil ever 3 batches.

Once you get your setup going, you will answer a lot of your own questions.

banger

waco
01-14-2014, 10:08 PM
Try preheating the boolits BEFORE you PC them. If its cold I think the powder will not adhere as well.
8-10 min. @ 400 Deg.

A pause for the COZ
01-15-2014, 09:57 AM
I gave one the hammer test, Smashed it flat and the coating held up just fine. So I was just being anal about the flashing around the gas check base.
I have some loaded up for a test run. head to head against same bullet standard lube.

http://i33.photobucket.com/albums/d66/Kelly2215/101_9117_zps9c79b372.jpg