Bond-o filler on rocket nosecone.

Automotive spot putty.

Mike Fisher

Great stuff; dries relatively quickly, sands very nicely!

-Kevin

I've been around industrial coatings and performed paint inspections to NACE standards for years and never saw or heard of anyone spraying primer and not sanding it. The anchor pattern left behind during the preliminary sanding of the rocket is the key to tight adhesion of the prime coat.

Always remember that the primer IS the paint job and all other coats after that are just color. If the paint chips down to the nose cone then the primer simply wasn't applied correctly. The problem of chipping usually stems from inadequate sanding of the surface or the primer was applied too heavily, that's why light coats are always recommended by paint manufacturers.

There are other reasons as well for paint not adhering correctly such as environmental conditions. Paint should never be applied if the surface temp does not have at least a five degree separation from the dew point and the humidity should always be below manufacturers recommendations.

I agree with everything else you wrote and I'll try the final light coat of primer and not sanding it just to see if it works! This old dawg likes to learn new tricks!

Andrew

You could try Selleys Heavy Duty Plasti-Bond......Not sure if you can get that brand??? Depends on what type of plastic the nose is made from??? Will not adhere to polyethylene, polypropylene or Teflon. Make sure the NC is clean........really clean. Use acetone etc. to remove any oils on the surface etc to aid in adhesion. May also help if you actually scar, scuff or put small pin holes in the area to filled. The filler is pushed into the hole and will provide a kind of rivet when it sets to help lock in the material....

This should be in the FAQ.

Yes, you did... you said it in all caps and twice in fact:

Rocket parts and industrial pipes and railings should be painted the same way. The paint has no idea what it is being sprayed on and will perform the same regardless of the surface as long as the coating is formulated for the intended application.

I've never heard of or seen a manufacturer recommendation or coating specification requirement for a seven degree separation between dew point and surface temp or needing a four hour window after coating before the temperature drops. Drops to what? From what?

I've never said you were wrong I simply stated that I've never seen or heard of some of the things you've mentioned. The only reason I even posted anything is because what you've stated is diametrically opposite of the industry accepted, case proven and manufacturer recommended methods used to apply a base then intermediate coating.

After some consideration I think leaving a light coat of primer unsanded would actually be detrimental to the next coating due to the loose adhesion characteristics and graininess, think about how easy it is to just rub off a light coating of primer. I think the smoothness of the intermediate coat would be less then ideal and with the potential for adhesion problems it may actually just peel off in sheets.

Andrew

Wow. Didn't mean to push you over the edge, I was just pointing out why the other person thought you said not to sand primer - because you did. I realize you didn't say NEVER to sand primer. I don't think anyone said you said that. :-)

Chill!

Thanks for all the great advice.

This nosecone is ABS, most of the ones I've worked with are PVC, ABS or PP, the PP is too soft and nothing sticks to it.

I searched the archives and heard people mention the body-filler and thought it would work just about the same as the model filler clay I had been using. But it sounds like it sands a lot easier. I will try the body filler, if it sands faster then it will be a 50% gain in time.

My process is pretty simple but lengthy: Scratch up the nose with 80grit sandpaper and apply a light coat of krylon ultra flat black (It seams to stick better then any primer I've tried) once the primer has dried it shows every imperfection, and I start sanding. Any pits, seams, cracks get a light fill of putty. Once dry I stand. Because it was a light coat I usually have to add 1-2 coats more of the putty to fill in all the cracks (the testors brand putty cracks in think layers and take a full day to dry if thick). I'll add a few layers of ultra flat to get a very smooth surface then lightly sand with 220 grit to better bond the final coats of paint. This method produced very nice results, but is very time consuming on larger surfaces.

-cat

Always sand the primer before applying paint, the paint before applying clear coat, etc..

Want better results? Use automotive "hi fill" primer out of a paint gun. Then you can sand/respray in minutes instead of hours, and it sands, fills, etc. much better than spray cans. WAY cheaper as well. Don't have paint equipment? Take the rocket to a body shop and ask about them hitting it with some primer next time they are doing another job. Should cost next to nothing.

I may not know much, but I know a thing or two about paint.

Try PlastiKote bumper primer from an auto parts store.