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Frustrated w/Kilz

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El Cheapo

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So I finally decided to try Kilz as a primer and quickly discovered it doesn't work well with wet sanding. Seems to be a bit too poreous even after two thick coats.

0906091052.jpg
 

troj

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Don't try wet-sanding water-based paints.

If you have a varnish-based version of Kilz, it should work. But I'm betting you're using a water-based version, and that won't wet-sand, as the water will just soften the Kilz.

-Kevin
 

El Cheapo

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Nope, the can says oil-based interior. The high spots seem to have dried and are not as pronounced as they are in the photo. Perhaps I didn't wait long enough to try wet sanding. I'll let it sit in the AZ sun all day and see if that makes a difference tomorrow.
 

JAL3

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Nope, the can says oil-based interior. The high spots seem to have dried and are not as pronounced as they are in the photo. Perhaps I didn't wait long enough to try wet sanding. I'll let it sit in the AZ sun all day and see if that makes a difference tomorrow.
I think that may be your problem. Kilz is thick stuff and takes a while to dry thoroughly.
 

troj

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Not that patient. :bang:
Find varnish-based versions, then -- enamels take a while to dry, varnish dries much faster, as do lacquers.

-Kevin
 

El Cheapo

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That or I can try a regular auto primer first to seal and then kilz to fill. These are not 2" conventional tubes but paper mailing tubes so that may have something to do with it as well.
 

BayouRat

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Duplicolor High Build Primmer. Laquer based. Dries fast. Sand in 30 minutes. Great stuff. You'll find it in the automotive section of Wall-Mart, Advanced Auto, etc..:D
 

Fade_to_Black

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Ditto on the Duplicolor. It's all I use. I tried KILZ once and it wrinkled up BAD when I sprayed Krylon on it. Ruined all the prep work on a really nice rocket. I had to strip it all off and start over. IMHO, KILZ is crap.
 

El Cheapo

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IMHO, KILZ is crap.
I'm beginning to think the same thing. It doesn't sand half as well dry as was mentioned. I would have been better off using fnf on the whole rocket and sanding that off.
 

powderburner

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Kilz is thick stuff and takes a while to dry thoroughly.
After spraying kilz, I let it sit for at least a week before trying to sand it. Even then, it does tend to load up the sandpaper quickly (but it DOES fill great!).

Something to keep in mind about kilz: while it is great at filling rough surfaces, this product is primarily a stain killer. That is, it is intended to be used over one kind of paint to stop it from bleeding through a different paint topcoat, or over fire-damaged surfaces to keep the char discoloration from distorting new paint. I don't think it is mainly a primer, at least not compared to other "primer" products, and I am not sure that it is designed to give really good adhesion to other topcoat paints.

After sanding it smooth, and moving to the paint stages, I have had a few experiences with kilz where the new paint does not stick quite so well to the kilz. Paint peeled right off one job when I used masking, and a couple other times the paint seemed to "fine" off the kilz pretty easily. Might have been just some paint-chem-compatibility thing, but I am thinking that after I use up my current supply of kilz that I would try the automotive primers that these other guys are recommending.
 

troj

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For filling spirals, etc, it's tough to beat a spot putty -- that's what it's designed to do. And they dry fast and sand easily.

Use a high solids primer to fill in small spots; using it to fill a spiral just isn't a primer's strong suit.

-Kevin
 

El Cheapo

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I used fnf to fill the spirals but thought I'd give kilz a whirl to fill the smaller imperfections. It's clear that I sprayed it on too thick and didn't realize it takes so long to completely cure. I can rarely let anything sit for a week let alone something in the finishing stages. I'm going to try for an L1 cert with this rocket next weekend so wanted some paint on it as it's already flown nekid twice. This may be a decent product for our use given some practice and patience but patience is just not one of my better virtues.
 

Trident

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What everyone else said ...

Kilz sands off like talcum powder, but you need to let it sit for a LONG time. Even in arid Colorado, I'd let it sit a few days.

I've a big fan of the Duplicolor primer -- lacquer-based anything dried fast.

If I were doing HPR, and filling plywood fin grain, I'd use Kilz again. I'm back to LPR/MPR only, and Kilz is not part of the solution for me any longer.
 

bacasino

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Interesting, Ive always had great success with Kilz. I spray a fairly heavy even coat. Wait 30 minutes. Sand with medium grit, then fine grit. Primer it with the same brand of color paint i am going to use. Light sand and paint. Fills great, looks great......It least i think. Might have to try the dupli-color for comparison.

http://public.fotki.com/bacasino/rockets/
 
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troj

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I used fnf to fill the spirals but thought I'd give kilz a whirl to fill the smaller imperfections.
Lacquer-based Duplicolor primer is the perfect product for you, then.

-Kevin
 

troj

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If I were doing HPR, and filling plywood fin grain, I'd use Kilz again. I'm back to LPR/MPR only, and Kilz is not part of the solution for me any longer.
FWIW, thinned epoxy will also work very well.

I filled the grain of a basswood nosecone and transition with laminating epoxy, and the amount of sanding required was minimal.

-Kevin
 

MarkII

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FWIW, thinned epoxy will also work very well.

I filled the grain of a basswood nosecone and transition with laminating epoxy, and the amount of sanding required was minimal.

-Kevin
http://www.bsi-inc.com/Pages/hobby/epoxies.html

Scroll down to the 20-minute Finish Cure epoxy. I have used this successfully in balsa nose cones, so I'm sure that it will work on plywood or basswood fins, too. Unlike most epoxies, it sands easily.

For filling deeper imperfections, this stuff works great, too.

Also, add my name to the growing list of fans of Dupli-Color High Build Primer.

MarkII
 

troj

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http://www.bsi-inc.com/Pages/hobby/epoxies.html

Scroll down to the 20-minute Finish Cure epoxy. I have used this successfully in balsa nose cones, so I'm sure that it will work on plywood or basswood fins, too. Unlike most epoxies, it sands easily.
Any epoxy, thinned with acetone, will work quite nicely, and sand easily. Saves you from buying extra epoxy.

Note that thinned epoxy is weaker, but if you're using it as a filler, who cares?

For filling deeper imperfections, this stuff works great, too.
Good stuff. Poly-Fil is a very similar product.

-Kevin
 

RangerStl

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I've also noticed that wet sanding is not a good way to go with Kilz. I had a tube start to swell and peel.

Phooey.

If it's dry, it dry sands pretty good. However, getting it to dry is kind of difficult if there is any humidity.

N
 

rocketguy101

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I have to wonder if Kilz, like Krylon, had to change formulas for EPA reasons. I say this because I used to have great success w/ Kilz from the rattlecan. I could wet sand it, and a single coat filled slight imperfections (after sanding FnF, etc). It was great stuff.

The last few cans I have used spray on too dry, leaving pores and sometimes just flaking off. I nearly ruined my beloved Centuri Sat V because the spray blobbed on, and really made the plastic wraps look crappy. I thought it was me, until reading this thread.

I know there was a new formulation, but it used to say on the label -- something like low odor, or such. Enviro regs are going to be the death of us all!! :)
 

MarkII

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I have to wonder if Kilz, like Krylon, had to change formulas for EPA reasons. I say this because I used to have great success w/ Kilz from the rattlecan. I could wet sand it, and a single coat filled slight imperfections (after sanding FnF, etc). It was great stuff.

The last few cans I have used spray on too dry, leaving pores and sometimes just flaking off. I nearly ruined my beloved Centuri Sat V because the spray blobbed on, and really made the plastic wraps look crappy. I thought it was me, until reading this thread.

I know there was a new formulation, but it used to say on the label -- something like low odor, or such. Enviro regs are going to be the death of us all!! :)
I believe that there are two types of Kilz being sold. The people who use it (I'm not one of them) recommend using the Original Kilz, which is readily available (and in fact, it seems to be the variety that is most commonly stocked, from what I have seen).

I believe that Krylon changed its formulation for its general purpose spray paint for marketing reasons, not due to some intrusive regulation. (The Bush administration wasn't exactly overrun with environmentalists, yet that is when the change occurred.) They still make plenty of the old formula, too.

Given its quite variable (or sketchy) performance, I would never use Kilz on something so critical.

MarkII
 
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Trident

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I nearly ruined my beloved Centuri Sat V because the spray blobbed on, and really made the plastic wraps look crappy.
I'd never use Kilz on plastic. It was meant as a sealer for porous surfaces, such as sealing stains on drywall, sealing in dark colors when repainting a room in light colors, etc. The plastic on the Saturn V probably needs no primer, or a super light coat of an automotive type primer, at most. Kilz has WAY too many fillers for plastic. And I'm not sure it would really bond with plastic.

I'd let it dry many days to make sure it is completely dry, and then try to sand it down.
 

MarkII

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The solvents in automotive primers will soften up thin styrene and can even cause it to deform. I found that out the hard way.

MarkII
 

RangerStl

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And I'm not sure it would really bond with plastic.
Krylon primer didn't bond too well with plastic either when I tried it. I never tried Kilz on plastic. If the plastic cone has any molded detail on it I would definitely NOT use Kilz even if it does stick.

If you can get the colors to match, plastic model paint in a spray can or air brish would probably be best on plastic parts. Always wash the plastic with mild dish detergent and water before painting to remove mold release agents.
 

Stymye

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I would not reccomend "wet sanding" any primer if at all possible.

the reason being that we are usually priming onto an absorbent cardboard surface, not a metal car body.

also primers are somewhat absorbent as well, if you paint over wetsanded killz without it >fully< drying you will have problems with cracking,flaking ect...and wrongfully blame the killz for the poor results.

Some important tips I have learned-
shake the heck out of the can and than shake some more,Kills needs to be mixed very thouroghly.

do not put it on too thick or pinholes will result(and it will take forever to cure)

allow several days to dry,once fully cured it will dry sand great ,pouring off in sheets of talc-like powder.

and most important -don't get in a hurry
 
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El Cheapo

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Now you tell me...lol All in all it turned out pretty good but alot of extra work.
 

MarkII

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I would not reccomend "wet sanding" any primer if at all possible.
I wet-sand my sealer/filler coats on nose cones and fins (after first sealing the balsa), but I rarely wet-sand anything on the airframe. I lightly dry-sand the primer layer, which is usually sufficient; if there is any rough spots in the primer layer after that, I add another coat of high-build primer to fill them in. But a couple of coats of primer has always been enough. Getting your rattle-can application technique down, so that you can give the rocket light, even coats really helps. I don't know about Kilz, since I have never used it, but with other primers (like Krylon or Dupli-Color), if you apply them well then you shouldn't need to do very much sanding. If I ever have any really rough spots left after lightly sanding the second coat of primer (it has happened a couple of times), I sand everything down bare and start over, rather than keep adding more primer. I learned awhile ago that thick coats of primer on rocket body tubes will lead to paint chipping very easily. Although I use Dupli-Color High Build Primer, I don't use it to try to cover over any surface defects, including visible spiral grooves. The time to correct those problem areas is before you start applying primer.

and most important -don't get in a hurry
Always good advice when you are painting, no matter what type or brand of products you use. Work methodically and thoughtfully, one step at a time. Don't try to rush things or combine steps.

MarkII
 

Pat_B

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A part of the market for the Kilz spray version is spraying over graffiti and stains on walls and ceilings of houses. Both applications require quite a bit of material to be sprayed from the can and that's part of the reason why it comes out so fast and thick.

I've had poor luck with Kilz. It's also a softer type product that works well on drywall (after sanding) when used with light coats, but thicker coats to fill spirals results in a surface that scratches and dents easily. It just wasn't intended to be a filler.
 
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