Primer and Paint compatibility

[cjp987]

Hi Everyone,

I'm sort of new to rocketry. Did it as a kid, and now 30 years later restarting the hobby with my son. We built a couple of rockets a couple of months ago. Had some painting issues that I think I've worked out. We're building 6 new rockets now.

I'm making some changes in my paint and primer choices, and want to make sure I'm not making any mistakes. I know you only put lacquers over lacquers, and not over enamels or acrylics, but I'm real confused on what's acrylic, enamel, or lacquer when the label doesn't clearly state. Here's what I'm using (maybe someone can tell me which category each of these fit into):

• Primer - Rust-oleum Painters's Touch primer (multi-purpose latext paint). This is a small can that is applied with a brush. 2 to 4 hour dry time. I will use it on the balsa parts.
• Primer - Rust-oleum Painters's Touch Ultra Cover 2x Primer.
• Primer - Rust-oleum Specialty Plastic Primer (for plastic nose cones)
• Paint - Rusto-oleum Stops Rust Gloss Protective Enamel
• Clear Coat -Rust-oluem Painter's Touch Ultra Cover 2x Gloss Clear

The painting plan is:

• Prime tubes with the 2x primer
• Prime plastic nose cones with the plastic primer
• Assemble rocket
• Prime fins and balsa nose cones with the brushed on latex primer. I prefer this approach over spraying since I find it hard to spray prime the fins due to the edges and angles, and the tubes will already be primed.
• Prime entire rocket (sans nose cone) with one additional coat of 2x primer. Lightly sand.
• Paint with gloss enamel (2 coats a few minutes apart)
• Wait 4-7 days
• Apply decals
• Paint with gloss clear coat (2 coats a few minutes apart)

I know everyone has their preferences on how to go about this and products to choose. I'm mostly just asking if you see any paint compatibility problems, especially since I have 3 different primers involved.

thanks,

Chris

 

[Marc_G]

Hi Chris,

Nice documentation. Great job.

You've managed to pick some of the few products I don't have much experience with so I can't help too much.

I have heard that the plastic primer has a very extended cure time... a week or greater... but I haven't used it personally.

The gloss protective enamel has worked well in my hands though I don't use it much now (I've generally moved from enamels to lacquers and water based acrylics). It has had a tendency to blush (milky color) due to humidity so follow the instructions on the can carefully with regard to the spraying environment.

Good luck. Looking forward to pictures.

Marc

 

[cjp987]

I've read the same about the plastic primer. The nose cones are already primed with it. Probably will be a total of 2-3 weeks before they are painted, so it should be well cured.

For the humidity, I'm in CA, so it is normally very low.

 

[o1d_dude]

I have heard that the plastic primer has a very extended cure time... a week or greater... but I haven't used it personally.

I have used it extensively and swear by it.

Here's what the directions on the can say on that re-coat times.

"Dries to touch in 20 minutes and dries to handle in 1 hour a 70 degrees (21 degrees C) - 50% relative humidity. Top coat after 1 hour. Maximum adhesion and durability will be achieved in 5-7 days. Allow more time at cooler temperatures."

There are two ways of reading this advice. I prefer to wait until maximum adhesion and durability are achieved because I sand the primer before applying the applying color coats. Here's why: I scuff the nosecone with 60-80 grit paper to raise "hair" before applying primer. The "hair" gives the primer additional surface area on which to get a grip. The plastic primer will be a bit rough so I apply a second layer (normal primer) and sand it smooth. Repeat as needed until the surface is smooth. Then I apply color coats. My nosecones rarely chip so I take this as a validation of the method.

If you don't plan to sand nosecone before priming or sand the primed surface, go right ahead and apply your color after the 1 hour specified.

 

[cjp987]

I have used it extensively and swear by it.

Here's what the directions on the can say on that re-coat times.

"Dries to touch in 20 minutes and dries to handle in 1 hour a 70 degrees (21 degrees C) - 50% relative humidity. Top coat after 1 hour. Maximum adhesion and durability will be achieved in 5-7 days. Allow more time at cooler temperatures."

There are two ways of reading this advice. I prefer to wait until maximum adhesion and durability are achieved because I sand the primer before applying the applying color coats. Here's why: I scuff the nosecone with 60-80 grit paper to raise "hair" before applying primer. The "hair" gives the primer additional surface area on which to get a grip. The plastic primer will be a bit rough so I apply a second layer of primer of normal primer and sand it smooth. Repeat as needed until the surface is smooth. Then I apply color coats. My nosecones rarely chip so I take this as a validation of the method.

If you don't plan to sand nosecone before priming or sand the primed surface, go right ahead and apply your color after the 1 hour specified.

I sanded first with 100 grit, and then applied two coats of the plastic primer about an hour apart. Are you saying that a 2nd coat of normal primer would be better (or add it as a 3rd coat at this point).

 

[o1d_dude]

I suppose you could apply a second coat of plastic primer but I don't really see any advantage to do that. Plastic primer is a bit more expensive than the "normal" stuff.

Once you've primed your plastic nosecone with the plastic primer, you should be able to apply additional coats of a compatible "normal" primer assuming the first coat is cured. I use the Rustoleum Plastic Primer from Autozone, wait 5-7 days, and then follow up with regular Rustoleum 2X white primer. No compatibility issues thus far.

When all is said and done, there might be as many as three to four coats of primer (1 plastic and 2-3 regular) in total before I shoot color. Overkill? Maybe.

 

[boomtube]

This topic is far more complex than “Paint/Primer compatibility; it also must include what material you are painting.

I have used Krylon paint/primer on virtually every type of tubing and nose cone material commonly available with no problems, same with Testors enamels and lacquers. . .Until I attempted to paint the nose cone of by “Blue Phoenix Jr.”

The primer went on perfectly yet when I sprayed the color-coat the paint and primer lifted up in big wrinkles and bubbles.

Taking it down to a local auto paint/body shop I enquired of the owner “What the f*&k?”
His answer was to sand it down to the base material and omit the primer altogether.
There’s an “Airplane” joke in that sentence somewhere but I won’t go there.

I have since encountered that same effect, (Affect? I can never keep those two straight) on a couple of other occasions where the application of the color coat causes the primer to lift off the painted object.

Material type makes a difference.

Good luck.

 

[Marc_G]

I have since encountered that same effect, (Affect? I can never keep those two straight).

See this clarification of the uses. Generally speaking, effect is used as a noun. Affect is used as a verb.

"You can get great effects with rattlecan paints, but be careful to prime the surfaces properly. The material being painted will affect the adhesion of the paint."

 

[cjp987]

This topic is far more complex than “Paint/Primer compatibility; it also must include what material you are painting.

All parts are from Estes.

• Plastic nose cones are P/N 072602 PNC-20A and P/N 071014 PNC-60AH.
• Some nose cones are balsa.
• Fins are balsa.
• Body tubes are cardboard.

thanks,

Chris

 

[boomtube]

Some of the plastic nose cones coming out of China these days have a waxy feel to them. This is not a coating or mold release compound; it is the nature of whatever type of plastic they are using.

Best guess; recycled beach balls mixed with whatever toxic/radioactive waste/s they have lying around. It’s a good way to get it out of their country and have somebody else pay for the privilege. My next guess is too terrible to mention; think Soylent Green!!

I personally don’t recommend priming this stuff as I’ve had numerous primer/paint/plastic separation events when I have used primer. The best paint I have encountered for this cra. . .stuff is Krylon “Fusion for Plastic”.

I’ve had some of these types of cones wherein the paint never completely dried. Days later and you could leave fingerprints in the paint.

I can’t recall ever getting one of these types of cones in an Estes kit, but; as all of the plastic parts for all rocket kits come from only one or two factories I figure it is only a matter of time before I do.

 

[cjp987]

Hi Chris,
...
Good luck. Looking forward to pictures.

Marc

Ok, here's the first of them. My son and I have 7 rockets in the pipeline. This is the first to come through, an Estes Hi-Flier. Still needs a gloss coat over the decal, although there is a gloss coat under it (the gold paint didn't take the decal well). Trying to decide if I want to do a bit of detail on the fins before I do the final gloss coat(s).

https://gallery.me.com/chris.plummer#100043

 

[Aksrockets]

I wouldnt recommend priming BEFORE assembling. Filling spirals is one thing, putting on a coat of primer is another. Unless this is a TTW finned rocket you will be gluing directly to the primer which doesnt allow the glue to soak into the tube. I suppose you could just rough up the tube (A LOT) before attaching the fins.

Alex

EDIT: High flier looks great BTW!

 

[cjp987]

I wouldnt recommend priming BEFORE assembling. Filling spirals is one thing, putting on a coat of primer is another. Unless this is a TTW finned rocket you will be gluing directly to the primer which doesnt allow the glue to soak into the tube. I suppose you could just rough up the tube (A LOT) before attaching the fins.

Alex

EDIT: High flier looks great BTW!

Thanks!

I've heard it both ways on the assembly/priming order. You point out the disadvantage of priming first. The disadvantage of assembly first is that it is a lot harder to prime and smooth out the BT with the fins in place. I know that was a big why I primed the BT first. I'm not sure if you noticed, but my engine hook is actually piano wire running along the fin fillets. I was worried that flexing it when adding/removing the engine would fatigue the fillets, resulting in cracking. Because of this I put the engine hook retainer ring at the very base of the BT. This then looked rather ugly, and a simple glue fillet was not enough to hide it. I ended using Elmer's wood filler to make a taper about 1/2" long. If you look closely, you can see the BT flare out slightly at the base. I could never have gotten this flare to look as nice as it does if the fins were in place already.

Anyway, I did rough the primer before gluing the fins. I used 220 grit. I probably should use something more coarse next time.

 

[cjp987]

I've updated the gallery with some additional pictures that show some ideas I have for painting the fins. I'm partial to the one with both red and black, although it's also the hardest to do.

https://gallery.me.com/chris.plummer#100043