Wet sanding

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Steven88

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Would you give me a few tips on wet sanding my rocket? It has Loc paper tubes. I have never wet sanded my rockets and it usually takes me several evenings and can really stretch out to prime and paint it as I wait for it to dry between coats for sanding on the primer and then wait 48 hours between paint of different colors so it doesn’t ‘lift’ on me. By the time I’m done I feel like painting it was almost as much work as building it. Maybe that’s just how it is for a nice paint job, but any tips to speed it up without sacrificing the paint job would be appreciated. Thanks
 
I have a tall thin box that I put rockets in to cure. A small space heater blows in at the bottom. Inside the box stays close to 120*f. And cures paint much faster.

But a good paint job just takes that long. I think its always more effort to paint it, then to build it.
 
Maybe that’s just how it is for a nice paint job, but any tips to speed it up without sacrificing the paint job would be appreciated. Thanks

But a good paint job just takes that long. I think its always more effort to paint it, then to build it

A GREAT paint job can be very time consuming, especially if you are doing multiple colors and have to include the 48+ hours between colors. It also depends on the complexity of the paint scheme and the complexity of the rocket (just 2 colors or 3, 4, more? 3FNC or some sci-fi type rocket with multiple surfaces?). Are you going for that "show room" appearance????

An OK paint job, one that looks good from 5' (or more) away, need not take a lot of effort (but you still need to allow for the drying times)

And there are those that do the initial launch without paint feeling that the rocket needs to earn its paint (and saves time if the rocket is lost, CATO, or otherwise become "unworthy" of painting)

But to your original question, you will more be doing damp sanding with the cardboard rather then wet sanding. Wet sanding really works best on FG or CF materials where you can slop a lot of water on the materials, but can be done carefully on cardboard and wood fins.

Have a container of water. Keep some paper towels handy. Soak the sandpaper in the water. Shake a lot of the water out and sand. You will end up with a bit of a slurry of the sanded material mixed with the water. When the paper starts to clog or the amount of slurry seems to be getting excessive, rinse the sand paper in the water and repeat. Use the paper towels to wipe off the excess slurry. NOTE - be careful not to sand down into the tube with the wet sandpaper, otherwise you will need to wait for the tube to dry before you can do more painting. I would practice on a spare tube before you risk the rocket.
 
Apologies if I missed it, but....

DO NOT wet sand paper tubes. The glassine layer on top will be affected and you'll have a fuzzy mess.

Get a coat of primer on there to seal the surface and then wet or dry sand to your heart's content. I *think* you implied primer first and wet sanding between coats in the original post, but wanted to be sure.

...back to your regularly scheduled programming.
 
Is somewhere from a 300-600 grit sand paper good for wet sanding?

Yes, that is pretty much the range for wet sanding, depending on what stage your rocket is at.
For sanding primer, I use 320 grit DRY to get it smooth.
But than again, I build up with many coats of contrasting colors as a "guild" to fill the
spirals and "rats in a gunny sack" texture without any sanding in between primer coats.
That way I Can sand down and hit a certain "color", then check the filling and either continue sanding dry, or apply more primer and repeat.
After all that, and spirals are filled I'll do a "check sand" (usually dry with NON wet or dry paper) to make sure there are no missed spirals or paper tube popping up under the last sanding.
After all THAT, I'll add at least coat or 2 of primer, then I'll wet sand with 400 grit wet or dry sandpaper, pretty much as les has mentioned above using a bowl of water and sand/wipe dry/repeat and check again for missed spirals and high/low spots,
once the primer is complete and the body tube is covered, you can wet sand if you don't use too much water.
If I find a missed spiral, I'll prime over that area and sand smooth again.

As far as color sanding the paint goes, wet sanding shouldn't be a problem as long as it again aint too wet because the BTs are now pretty much sealed.
Hope that helps, that's just the way I do it. :cool:
 
Apologies if I missed it, but....

DO NOT wet sand paper tubes. The glassine layer on top will be affected and you'll have a fuzzy mess.

Get a coat of primer on there to seal the surface and then wet or dry sand to your heart's content. I *think* you implied primer first and wet sanding between coats in the original post, but wanted to be sure.

...back to your regularly scheduled programming.

GOOD POINT!!!
Yes, glassine, scuff it lightly first with 240ish grit to break the gloss and then I always use Dupli-Color Self Etching primer as my first primer coat.
It helps bond to the glassine AND the plastic nose cone! PLUS it's OD Green! That makes me feel BETTER! LOL

And, I don't like to scuff paper (un-glassined) body tubes wet or dry, that's why I use the self-etching as the first primer coat.

Thanks ECayemberg!!!!
 
By the time I’m done I feel like painting it was almost as much work as building it.
That is fairly normal for a lot of us.

Windex. Use it for all my wet sanding. Slicker than water, keeps paper from clogging better, evaporates faster than water.
Haven't heard that one before. Does the blue coloring infect the paint at all?
 
Applying a good paint job can easily take every bit as long as the construction of the rocket. I generally start with 400-600 on the primer coats, then 400 through 1500 on the paint. A coat of Rustoleum that ends up bumpy (orange peel) will take quite a while to make look great, and sometimes I decide that perfection is the enemy of good enough, put the vinyl and clear coat on, and call it good. But I have never regretted putting too much work into the paint work.
 
Windex does not discolor paint. A paint job is 99% surface prep, if you can see it, or feel it, paint will NOT hide it. As far as grit goes, it all depends on what you need to do. If you are removing flaws, runs, sags, bug flew into it, I like to start with 800 grit. This will be fast removal, do not sand through. Then I will progress to 1000, 1500 and finally 2000 grit, which will polish out very nicely. I myself, never wet sand primer. From 100 grit to 400 grit for primer, with the last being with a maroon scotchbrite pad.
 
There should be a thread on this if you search the forum. Paper tubes just be careful not to soak the tube and limit yourself more to "damp" sanding the surface and always wipe excess immediately. If it a warm sunny day I like to let the tube dry in the after wiping before applying any paint etc. I would start with 600 / 800 and finish with 1000 grit wet/dry paper
 
Windex. Use it for all my wet sanding. Slicker than water, keeps paper from clogging better, evaporates faster than water.

My issue with Windex is the smell.

There actually is a lubricant that’s pretty much perfect (assuming you’re sanding primer and not paper tube): go to the auto care section of your Walmart and get some clay lubricant (many double as “quick detailers”). Super slick stuff, and some of them smell really good. (Meguiars Quik Detailer smells good)

It’s also meant to be a light-duty cleaner for auto paint, and its blue coloring doesn’t stain. Some market themselves as zero residue - and you can clean glass with it too.
 
Apologies if I missed it, but....

DO NOT wet sand paper tubes. The glassine layer on top will be affected and you'll have a fuzzy mess.

Get a coat of primer on there to seal the surface and then wet or dry sand to your heart's content. I *think* you implied primer first and wet sanding between coats in the original post, but wanted to be sure.

...back to your regularly scheduled programming.
Suggest that you deal in the inside of the tube with an oil-based sanding sealer. Any water that gets inside the tube during the sanding process will damage the tube. Besides, it makes makes wiping BP residue out a breeze.
 
I never seen a need to wet sand to get a nice finish. Perfecting paint application is the key. Once the model starts flying that perfect finish will be no longer anyway.
 
Very seldom would I wet sand primer. But, if there is a flaw, I will wet sand color. Usually a good scuffing with a maroon scotchbrite pad between color and clear will do.
 
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Do you guys typically sand between actual coats of paint or just after you prime?

Depends on a few things - the paint being a big one.

If it isn’t smooth, yes. I’ll sand color; I even did it yesterday - though not necessary wet; some acrylic paints would come off completely with wet sanding.

Some (automotive) paints require the color to be coated with an intercoat clear within a hour of spraying the color. If you don’t, you have to scuff the paint and re-shoot the color...

A “polished” finish means you’ve shot clear over the color, and sanded the clear flat (to flatten masking & tape lines), shot more clear, and then sanded with 1500, 2000, 3000, buffed with compound and finally a polishing compound. At that point, it’s not humanly possible to sand any smoother, and looks wet & shiny.
 
Do you guys typically sand between actual coats of paint or just after you prime?
Generally only between primer coats and after the final primer coat. But if I get runs or other issues with the color coat, I'll wait until it's safe and wet sand the color coat to fix any issues then continue painting.

Windex is about 95% water with some additives. The advantage that that Windex adds is the surfactants, which keep the paint particles suspended in water so they flow off the surface better, and helps it dry faster since the surfactants help the water sheet, rather than stand in big droplets.

The only rockets I really go crazy on trying to get a super smooth are carbon fiber MD rockets where the smooth surface can make a difference as far as altitude is concerned. (I have samples from 38mm to 98mm). Otherwise I go for 'good enough from 10 feet'.


Tony
 
Do you guys typically sand between actual coats of paint or just after you prime?
This is a good question that I often fret over: when to sand? There are many possible answers, and many variables, including the type of paint you use. In general there is no doubt that good surface pref (including sanding) is a major contributor to the quality of the final finish.

Obviously, filler/primer is *always* sanded. I usually sand down to 400 grit.

If I do a separate white primer coat then I'll give it a quick sanding, nothing elaborate because I find the primer tends to go on fairly smooth in the first place. But there are always some imperfections. I don't go crazy here because of what I describe next.

The final paint coats are were it gets interesting. With Rusto 2x, I have found consistently that the best finish is obtained if the paint is sanded prior to the final heavy coat. This is annoying because it adds days to the painting process, but that's the way it is. What I'll usually do now is apply all the usual 2 light coats + final heavy coat, and then evaluate it when it's dry. If I'm sufficiently dissatisfied with it then I'll sand it and then reapply another final heavy coat, and that is almost always very good.

By contrast, the Rusto Stops Rust Metallics are thinner and go on very smooth, and in my experience the final sanding is not necessary. If you start with a smooth primed surface, then you will end up with an excellent finish without any further sanding.

Ultimately you need to find the balance of effort and results that makes you happy.
 
Applying a good paint job can easily take every bit as long as the construction of the rocket. I generally start with 400-600 on the primer coats, then 400 through 1500 on the paint. A coat of Rustoleum that ends up bumpy (orange peel) will take quite a while to make look great, and sometimes I decide that perfection is the enemy of good enough, put the vinyl and clear coat on, and call it good. But I have never regretted putting too much work into the paint work.
My Zephyr Jr has been contaminated with outside debris. Used 800 grit on my white top coat and accidentally sanded down to the primer on a spot, could have been I got carried away. Switched to 1000 grit, I noticed I was able to sand down the orange peel to ~ 10%.

With 800 I had ~ 25% of the orange peel left

I’m enjoying wet sanding the paint coat, I can do it in my bedroom over a towel without making a mess, compared to dry sanding the primers / fillers in the building stages
 
Windex does not discolor paint. A paint job is 99% surface prep, if you can see it, or feel it, paint will NOT hide it. As far as grit goes, it all depends on what you need to do. If you are removing flaws, runs, sags, bug flew into it, I like to start with 800 grit. This will be fast removal, do not sand through. Then I will progress to 1000, 1500 and finally 2000 grit, which will polish out very nicely. I myself, never wet sand primer. From 100 grit to 400 grit for primer, with the last being with a maroon scotchbrite pad.
I sanded my topcoat with 800 grit since i had a contaminated coat with orange peel on my MPR.

I noticed I was able to sand down the paint to ~25% orange peel. Luck ram out when I sanded through the top coat. Switched to 1000 grit, brought it down to 10% orange peel. I can attest to your statement
 
I even wet sand my primer, although I would never try it in my bedroom! Way too much water and sanding material saturated drops flying and dripping all over the place.
I place a towel under the rocket and wipe after every time I stop sanding to check over the spot I sanded. I’ve tried with primer, and yes, it’s definitely a ‘milkier’ color
 
@Nathan sands the clear coat with 1000, then 2000, then machine buffs with polishing compound:
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