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les
22nd January 2011, 02:42 AM
I have a plastic nose cone that I used the Rustoleum Plastic primer on.

It did not appear to be sandable, so I gave it a shot of regular Rustoleum primer and went to bed. I checked up on it in the morning, and the top primer is all crazed. :y:

Suggestions? :confused:

degreaser
22nd January 2011, 03:21 AM
How long did you let the plastic primer cure? What was the temperature when you applied the second primer coat. Can you sand it down?

The instructions on my can indicate one thin primer coat is preferable to multiple primer coats and that best adhesion occurs after 5-7 days.

I have a few PML plastic nosecones that I plan to prime using the Rustoleum plastic primer so this is definitely of interest to me.

les
22nd January 2011, 03:44 AM
I let it cure about 2 hours.

Not sure on the temp (it is cold outside, but I have a "sealed" area with a heater to keep it warm.) The can does say it is dry in 1 hour.

I did some sanding, but have not removed all the top primer. I will need to hit it again. Or should I sand all the top primer off? And if I do, how will I know if the Rustoleum paint I plan to use won't do the same???

troj
22nd January 2011, 03:52 AM
What's the recoat window? And what's the temperature inside your 'sealed' area? What does the can say for application temperatures?

It makes a difference...

-Kevin

o1d_dude
22nd January 2011, 04:02 AM
If you sand the nose cone with an aggressive grit (80-120) before priming, you will raise a lot of "hair" that will not show up until you hit the nose cone with the primer. The "hair" is a good thing because it provides a good grip for the primer. The "hair" goes away after you sand the primer coat. This is an iterative process. Sand, prime, repeat. Eventually (3-4 coats) you will get the glass-like finish you crave. Then you shoot your color.

I just sprayed the BTH-80 nosecone for my Bottle Bat 2.6 with the Rustoleum Plastic Primer today.

BTW, did you wash the nosecone down with mineral spirits as called for by the directions on the can before shooting the Plastic Primer? Just wondering.

SAC of MMMSClub
22nd January 2011, 04:06 AM
I have had a similar problem on nose cone and epoxy fillets.
Wash in Dawn and hot water to get mold release off.
Wash with alcohol.
Sand, and wash with alcohol.
Prime, sand, wash with alcohol.
Paint, wet sand wash with alcohol.
And so on till you get the look you want.
Pain but it works.
It must have to do with oils, resins, acids, coming to the surface of the nose cone.
Was the plastic primer dry and 12 hours old or was it just beyond tacky? The combo may have nothing to do with it, you may have returned to crazed paint anyway if something was on the surface already.:confused2:
I wash a surface to be painted with alcohol just in case there is something that has come to the surface and is waiting to ruin the next coat.:bang:

-Scott

NAR#91379 L0

o1d_dude
22nd January 2011, 04:22 AM
I have heard that alcohol sometimes leaves a residue behind...impurities in it or some such. Haven't used it so I don't have first hand experience.

degreaser
22nd January 2011, 04:30 AM
Ok, While all of you guys were yackin', I'm trying an experiment :).

I just finished sanding a PML 3" nose cone with 120/180/220 grit to clean up the parting lines and rough it up a bit. Then I washed it twice with Dawn detergent, dried and masked off the coupler section. I applied a moderate coat of plastic primer.

It's definitely "fuzzy". I'll let it cure for a week and then sand and apply another coat and see what happens. Room temp was about 70 degrees.

The can doesn't say much about recoat but does say that you can apply a finish coat in an hour. That seems way too short in my mind but whatever...

les
22nd January 2011, 05:40 AM
I would say the temp was in the mid-60's, based on it "feels comforatble". I had sanded with 320 and washed the cone and wiped it down with acetone before the Plastic primer. The plastic primer did not appear to have any issues, but the can does not say anything about being sandable, which is why I added the other primer.

Since the can said you could top coat after an hour, I figured 2 hours was good before the regular primer. Most primers I've seen state you can top coat in about an hour.

I've sanded the top coat some and have done a second coat of the regular primer to fill in the crazing cracks. It looks OK now. I'll wait until morning to try to do the color coat.

gdiscenza
22nd January 2011, 05:08 PM
I have read that if you sand before you wash a nose cone, you will embed the release agents into the plastic and washing will not get them out.

My progression is usually as follows:

1) Wash with soap and very hot water
2) Dry and wipe with alcohol
3) Sand from 80 grit up to 220 grit, each grit erasing the scratches from the previous grit
4) Wipe with tack cloth
5) Bondo spot putty and repeat sanding
6) Wipe with tack cloth
7) Primer
8) Wait 48 hours then sand from 220 to 400
9) Primer
10) Wait 48 hours then sand from 220 to 400
11) Paint 3 coats like steps 7-10

Sometimes I skip a step, and usually regret it.

G.D.

SAC of MMMSClub
22nd January 2011, 07:02 PM
cq cq cq

cool, love a good experiment, must be all the MythBusters I watch with the kids.
What is the goal of the masking and what are you comparing it to?

-Scott

NAR#91379 L0

o1d_dude
22nd January 2011, 08:14 PM
cq cq cq

cool, love a good experiment, must be all the MythBusters I watch with the kids.
What is the goal of the masking and what are you comparing it to?

-Scott

NAR#91379 L0

Question wasn't directed at me but when has that ever stopped me from responding? Degreaser can jump in here as well.

I mask the bottom of the nose cone so as not to add thickness to the part that slides inside the airframe. Doesn't everyone do this? Asking because I've done this for years and it seems most of my rocket club members do this as well.

SAC of MMMSClub
22nd January 2011, 08:42 PM
Oopps, my bad..

Yes, I saw the masking on the shoulder, that I understand and agree with, what I thought was implied was masking of the exposed nose cone.

-Scott
NAR#91379 L0

degreaser
23rd January 2011, 04:00 AM
cool, love a good experiment, must be all the MythBusters I watch with the kids.
What is the goal of the masking and what are you comparing it to?

Pretty much like o1d_dude said :) The masking tape preserves the outside diameter of the nose cone coupler section and keeps it nice and slippery for ease of ejection.

Les is having difficulty and I'm trying (not) to reproduce it. I'm using plastic nose cones too and had planned to do almost exactly what he did. I'm lengthening the primer curing time though in the hope that the additional time will cure the problems. Standard primer sets up pretty quickly but this stuff evidently takes longer.

les
23rd January 2011, 04:40 AM
I was at the dollar store and bought a cheap garden thermometer. The temp in my area is about 70F.

Again, the "base" Plastic primer is not showing any problems (so I don't think there were any issues from the release film. It was the "regular primer" (can says automotive primer) that had a problem on top of the plastic primer. I can sand the top primer all off, but can I feel comfortable that the paint won't do the same?

degreaser
23rd January 2011, 04:58 AM
...I can sand the top primer all off, but can I feel comfortable that the paint won't do the same?

I think gdiscenza's, old_dudes and SAC's method looks good and with additional drying time it should form a good base for the finish coat(s). I need to apply a bit of Icing to mine to fill in some parting line imperfections but I'll wait until I'm completely done with the primer before attempting that.

My guess is that the second primer coat you used softened the underlying plastic primer coat and caused crazing. I'm thinking that if it's completely cured, that may not happen.

degreaser
28th January 2011, 07:23 AM
I sanded it down with 220 grit and washed with Dawn. The fuzzy surface is gone but it's still fairly rough. I'll hit it with another primer coat tomorrow night. It feels like it's adhering very well. The dust has an unusual texture though, sort of slippery like teflon.

o1d_dude
28th January 2011, 07:26 AM
I sanded mine down as well and got a satisfactory surface. Not a final surface mind you but I'm okay with it so far.

I think the "teflon" texture of the dust is related to the polypropylene threads in the primer.

ghrocketman
28th January 2011, 03:41 PM
Rust-Oleum automotive primer is LACQUER based and the Plastic Primer is ENAMEL based.
NEVER, EVER apply a Lacquer over an Enamel.
The Lacquer has "hot" solvents that WILL craze and ruin below coats of Enamel.
You CAN apply Enamel over Lacquer, but NEVER Lacquer over Enamel.

Your nose cone has a crazed finish because of this.
Sand it completely down and start again !

degreaser
28th January 2011, 08:18 PM
Curious - How do you transition from an enamel undercoat to a lacquer overcoat? Is there a paint/primer which would form a barrier coat available?

RangerStl
28th January 2011, 08:21 PM
I don't think you can. I recommend sanding all primer off and starting over. :(

plano-doug
28th January 2011, 08:38 PM
Curious - How do you transition from an enamel undercoat to a lacquer overcoat? Is there a paint/primer which would form a barrier coat available?After reading GH's response, ever so infomative as usual ;), I concluded that, in order to use the specialized plastic primer, you need to stick with enamel top coats, and hence lacquers are not an option.

Doug

.

degreaser
28th January 2011, 09:39 PM
I don't think you can. I recommend sanding all primer off and starting over. :(

Well, I haven't applied an automotive primer so I'm good to go. Les will probably need to sand it down though. I was considering using automotive primer as I wasn't aware of that problem nor was I aware that the plastic primer was enamel based.

eggplant
28th January 2011, 10:18 PM
Ok, While all of you guys were yackin', I'm trying an experiment :).

I just finished sanding a PML 3" nose cone with 120/180/220 grit to clean up the parting lines and rough it up a bit. Then I washed it twice with Dawn detergent, dried and masked off the coupler section. I applied a moderate coat of plastic primer.

It's definitely "fuzzy". I'll let it cure for a week and then sand and apply another coat and see what happens. Room temp was about 70 degrees.

The can doesn't say much about recoat but does say that you can apply a finish coat in an hour. That seems way too short in my mind but whatever...
Is that heathkit box a heathkit computer? :jaw:

o1d_dude
29th January 2011, 02:42 AM
Based on GH's information, I did a little research this afternoon at the local Home Despot.

The Rustoleum Automotive Primer as stated is most likely a lacquer primer so it shouldn't be used over the Plastic Primer.

The Rustoleum Painter's Touch Ultra Cover 2X Primer appears to be an enamel based on the recoat times.

The only time I've had an issues with Rustoleum Automotive Primer is when I've overcoated it with Plasti-Kote which caused it to craze a bit.

If you're going to paint with enamel, the plastic primer should work fine.

Adam Selene
29th January 2011, 03:38 AM
a couple of years back I contacted the manufacturer of the fussion paints for plastic and was told not to use ANY other kind of paint, including ANY kind of clear coat over it. Don't know if this applies to the rustoleum or not.

les
29th January 2011, 03:56 AM
I understand you can't put a lacquer over an enamel

I'm looking at the automotive primer can and I can't see where it states it is a lacquer. In says it is a good base for most lacquers and enamels, but to test any lacquers for compatability (it states you get best results with enamels)

Where does it say it is lacquer based?

But, bottom line - I've sanded it all down :(

o1d_dude
29th January 2011, 04:25 AM
It doesn't say "This is a LACQUER based product". What it does say "Recoat at any time".

Most enamel products will say you can recoat within an hour or after 24-48 hours.

les
29th January 2011, 04:59 AM
But the plastic primer says you can top coat anytime after 1 hour. So what defines it as an enamel? Again, the can does not say it is an enamel.

Confused....

degreaser
29th January 2011, 05:18 AM
Is that heathkit box a heathkit computer? :jaw:

IIRC, it's the box from a Heathkit 2718 bench power supply. :) 5v and dual adjustable 0-20v supplies.

There's a Heathkit H19 terminal elsewhere in the shop and a multimeter on top of my oscilloscope. I also have a few Heathkit amateur radios. Heathkits were great kits. It was a very sad day when they closed. Elecraft make cool kits too.

degreaser
29th January 2011, 05:28 AM
But the plastic primer says you can top coat anytime after 1 hour. So what defines it as an enamel? Again, the can does not say it is an enamel.

Confused....

FWIW, here's the MSDS. It doesn't say enamel. It contains lots of different solvents.

From
http://www.rustoleum.com/CBGProduct.asp?pid=379:

OVERVIEW:
Rust-OleumŽ Plastic Primer prepares interior and exterior plastic surfaces for painting with most brands of automotive lacquers and enamels. If using an auto lacquer, a test application for compatibility is required.

GregGleason
29th January 2011, 05:48 AM
I understand you can't put a lacquer over an enamel

I'm looking at the automotive primer can and I can't see where it states it is a lacquer. In says it is a good base for most lacquers and enamels, but to test any lacquers for compatability (it states you get best results with enamels)

Where does it say it is lacquer based?

But, bottom line - I've sanded it all down :(

You would have to look at the MSDS and look at the ingredient ratios of the "solvents package". If you see a "hotter" solvent like acetone, it's a lacquer.

For example, here are the ratios for the solvents package of Dupli-Color primer BPR0031:

% Wt | Ingredient
31 | Acetone
14 | Methyl Ethyl Ketone ACGIH TLV
11 | Propane ACGIH TLV
11 | Butane
7 | Ethyl 3-Ethoxypropionate ACGIH TLV
6 | Talc
4 | Titanium Dioxide
2 | Toluene
2 | Calcium Carbonate
1 | 2-Propanol ACGIH TLV
1 | 2-Methyl-1-propanol ACGIH TLV


Greg

degreaser
29th January 2011, 05:56 AM
If you see a "hotter" solvent like acetone, it's a lacquer.


Ok, it has that.

I guess it failed the compatibility test.

plano-doug
29th January 2011, 03:18 PM
If you see a "hotter" solvent like acetone, it's a lacquer.Not to mention 14% MEK ;)

Doug

.

bobkrech
29th January 2011, 03:50 PM
Just remember, it's the paint, not the primer, that's incompatible.

One of the solvents in the paint is attacking the primer.

Bob

Sailorbill
29th January 2011, 04:00 PM
Just remember, it's the paint, not the primer, that's incompatible.

One of the solvents in the paint is attacking the primer.

Bob

Bob
Both were primers.


I have a plastic nose cone that I used the Rustoleum Plastic primer on.

It did not appear to be sandable, so I gave it a shot of regular Rustoleum primer and went to bed. I checked up on it in the morning, and the top primer is all crazed.

degreaser
30th January 2011, 04:13 AM
Update - I applied a second plastic primer coat last night and sanded with 220 this evening. It's developing a very good primer base. The dust is very different from the first coat and feels more like normal primer dust - it's not at all slippery. One more coat, some Icing, sanding to 400 and I think it'll be good to go.

I wish they would tint it some color other than off-white.

degreaser
6th February 2011, 02:29 AM
I was about to apply some Icing (tm) to my nose cone to fill in the parting lines but then I read the label - it can't be applied over lacquer based primers. :bangpan:

I'm trying some Bondo glazing putty instead. It has some pretty strong solvents present but I'll take that chance. It sands very easily as well.

Assuming all goes well, some sanding, one more primer coat and it'll be ready for paint.

les
6th February 2011, 03:48 AM
FYI
I fully sanded mine down and used a different primer (Rustoleum self etching)
No issues

degreaser
6th February 2011, 04:13 AM
Good to know. Could you post an image of the can or SKU?

degreaser
6th February 2011, 05:09 AM
The glazing putty did a good job. It seems to adhere well to the primer and dries quickly. One more coat and it's done I think.

It seems a good long period between primer coats using the plastic primer works pretty well.

o1d_dude
6th February 2011, 06:15 AM
I let my nose cone cure for about a week after priming it with the Plastic Primer. The label may say something about doing that.

Anyway, after hitting it with the sandpaper, I laid down a second coat of primer but this time I used the Rustoleum Painter's Touch 2X white primer. No crackling so I sanded it again and gave it a third and final coat. After wet sanding the nose cone, it was as smooth as glass.

All things considered, I have to say the stuff works as advertised if you can wait the seven days to let it cure.

BTW, I painted the nosecone fluorescent pink. And the rest of rocket, too. BRIGHT!!

o1d_dude
28th February 2011, 09:43 PM
I bought my rattlecan of Plastic Primer at the local Autozone store. Oddly enough, the cap is a light gray but the paint itself is pure white. Go figure.

I use only a single light coat of the Plastic Primer and let it cure for at least a week before I do anything else with it.

Next step is to sand it down and apply another coat of white primer. From that point forward, it's just another nose cone and follows the usual steps. With one notable exception (a balsa nosecone and Testor's Purple-Licious rattlecan paint), I've never had an issue with nose cones. They all have come out slick and glassy.

There's a snapshot of the most recent one ('Big Pink') attached. It's done in Rustoleum Fluorescent Pink with two Rustoleum Crystal Clear Enamel overcoats. The tube fin trim color is Rustoleum Metallic Midnight Black.

Maybe it's just luck but if so, I'd rather be lucky than good. :wink:

Micromeister
28th February 2011, 10:13 PM
I have heard that alcohol sometimes leaves a residue behind...impurities in it or some such. Haven't used it so I don't have first hand experience.

NO alcohol does NOT leave a residue, Washing plastic in soap and water leaves a residue. Even 50% Alcohol is better the washing plastic parts in soap and water.

Captain Ron
28th February 2011, 10:16 PM
Amazing, i must be lucky or something because I never had any issues using Rustoleum or Krylon rattle can paints. I wash all plastic pieces with dish soap and warm water, lightly sand just to knock off any shine, prime, lightly sand again with 600, paint.... set off to the side, clear coat next week...
For body tubes I use a cheese cloth or similar tacky cloth before priming or painting....
I never use a paint thinner or similar solvent before applying anything because that may cause an adverse reaction with your paint, such as "orange peel"

It helps to wash your hands often too, especially after having a slice of meat lovers pizza before handling anything :D

KarlS
28th February 2011, 10:59 PM
Never use rubbing alcohol to clean parts. Use only denatured. Rubbing alcohol has an oil in it. Denatured does not.