Primer vs sandable primer

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PXR5

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I have been using sandable primer for several years, this weekend I ran out and called my associate who was at the dollar store shopping. I asked her to pick some up for me.

No luck, but she bought regular primer.
Well low and behold, what a dream to work with compared to the sandable.
It's lighter, not real heavy, I think the sandable would work better for auto body work YMMV
 

KILTED COWBOY

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I find the sandable primer works better for filling in defects.
I wonder how it would work if you used the sandable for the first coat or two then switch to the other type for the final coats before the color gets put on
 

neil_w

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Well, lots of primers are sandable. The key is that what many of us are using as the first coat is filler/primer, or high-build primer. This is the grey stuff with lots of solids in it to help fill in and smooth out surface imperfections. Normally, the goal with filler primer is to sand most of it off, and leave it only in the pits and cracks that it filled in. Because it goes on thick and heavy, and because you need to remove a lot of it, it invariably leads to a lot of sanding effort. Really, for a lot of us filler/primer really isn't there are a primer at all, it's there for its filling and smoothing properties. I often (depending on the topcoat color but also how lazy I'm feeling that day) apply a coat of regular primer over the sanded filler/primer, to provide a nice consistent base for the topcoat.

Regular old primer is usually sandable as well, but because it's not a high-build formula, it goes on in a much thinner coat and is easier to sand. Plus, with regular primer you're usually not trying to remove most of it. Regular primer will (like most paints) provide a *slight* bit of filling to imperfections, but usually not a significant amount unless you apply a *lot* of it.
 

Spitfire222

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I use the filler-primer during all of the prep work of smoothing and filling in imperfections of the basic structure. When the model is ready for paint, it gets a thin coat of "regular" primer, wet sanded, and then painted. My rockets might end up on the heavier side, but it doesn't concern me, since I'm not looking for maximum altitude. I enjoy having my rockets look good, and I'd like to get them back!
 

Funkworks

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... My rockets might end up on the heavier side, but it doesn't concern me, since I'm not looking for maximum altitude. I enjoy having my rockets look good, and I'd like to get them back!
My first guess is that any lack of performance caused by weight increase is compensated for by minimized drag. And as others have said, most of the primmer is sanded off anyway.

Hm. On my next build, I'll be making before-and-after weight measurements. Because now I'm wondering.
 

Nytrunner

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The rocket Noob did a series of posts about weight vs drag of painted vs unpainted models.

For a true comparison, you could build a rocket. Fly it naked, fly it primed, fly it sanded primer, fly it painted, and see whether there's any differ3nce other than noise
 

Off Grid Gecko

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My first guess is that any lack of performance caused by weight increase is compensated for by minimized drag. And as others have said, most of the primmer is sanded off anyway.

Hm. On my next build, I'll be making before-and-after weight measurements. Because now I'm wondering.
On that same note. Just checked my freshly painted bird after posting on another thread. It was 129 grams the other day (one day of drying, maybe less) and tonight it's 109. I checked my sim file to be sure (updated after the last weight measurement). There's a LOT of solvent in paint. I never realized how much. I plan on taking several weight measurements on my next build when I get to the painting stage.
PS, the last measurement may have been with the 8g chute, so that would make up for some of the difference.
 

rklapp

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I was having problems with Killz sandable giving cottage cheese. It’s fixable but annoying. The regular primer is easier to apply but needs more coats for the same effect. I’m okay with just two before color.

Quality is so hit or miss. I’m having great results lately with Rustoleum 2x white high gloss. The same yellow has been a nightmare.
 

BABAR

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I was having problems with Killz sandable giving cottage cheese. It’s fixable but annoying. The regular primer is easier to apply but needs more coats for the same effect. I’m okay with just two before color.

Quality is so hit or miss. I’m having great results lately with Rustoleum 2x white high gloss. The same yellow has been a nightmare.
Der MicroMiester passed before you came on the forum, he was both jack of AND master of all trades, and in fact I think his ACTUAL trade WAS painting signs. He said Yellow was the toughest rocket color to get right.
 

HHaase

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I picked up a hint in my miniatures painting hobby, before painting something yellow I used to always paint it tan, which worked great. But apparently if you paint something PINK first, they yellow just goes on like magic.

-Hans
 
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