Filler/Primer

[RCBrust]

I'm always on the lookout for better filler/primers. Recently I've settled on Dupli-Color FP102. It definitely fills nicely but it will gum up the sandpaper unless you let it dry for a while, like 5-10 days. Of course if what you painted lends itself to wet sanding, then it's not an issue but for dry sanding, I like to let it dry until I can't really smell it anymore if I put my nose right up to it.

A week or so ago I was watching a YT video of a 3D printing guy doing a filler/primer comparison and he liked the U-Pol brand. I decided to try U-Pol UP2722 Expert Sandable Primer that claims it's high build. My local Auto Zone had it and it was only like $10-$11. I tried it on a body tube that I had glassed and I have to say that it worked very well. As an experiment, I tried dry sanding it 2 hours after I sprayed it and it sanded nicely without gumming up the paper. I could still smell it so it wasn't fully dry, but still sanded fairly well. I let it dry overnight and the next day it had very little smell and sanded great.

So, I think I've found a new filler/primer. Auto Zone seems to be the only place that has it. Not sure if it's exclusive to them or not.

Randy

 

[lakeroadster]

Looks like it's priced right too. $10.99

https://www.autozone.com/paint-and-...e-primer/1244310_0_0?searchText=primer+up2722

 

[WizardOfBoz]

Good to know.

I've been using Rustoleum 2 in 1 filler and sandable primer. The wet sanding has gone well. I've done a little dry sanding after a few hours and it seems ok. But I haven't done the rigorous dry sanding that you've done. The Rustoleum seems to get good reviews and its a little cheaper (7.98/12 oz at Lowes). But it's nice to know of another good solution.

Given your title, I'll take another opportunity to thank @ECayemberg for the suggestion of using red glazing compound (I used Bondo's Glazing and Spot Putty) to smooth out rough epoxy fillets. I've also used it to fill in the grain on balsa, and to smooth the joints between coupled tubes. With the good filling and priming compound, I've gotten good results.

Also using Rustoleum Automotive Bonding primer for the plastic parts. Bonding primer, then sandable primer, then color. I suppose I'll clear coat at some point. It all seems to work ok.

All of this is under Krylon. Not sure I like the coverage of Krylon. Seems to take a lot of coats.

 

[RCBrust]

I basically don't use Rustoleum anything. I'm sure they have some decent products nowadays but it seemed like any Rustoleum I tried in the past didn't work well for me.

My process is that I start with a heavy coat of filler/primer. Then, as you mention above, I look over the model and anything that the filler/primer won't hide gets dabbed with red Bondo spot putty. The Bondo works well because it dries fast and it has a similar "sandability" as the filler/primer. I then almost completely sand away the filler/primer/Bondo until only the areas that needed filling are left (see pic). That's why I like this layer to be very sandable. I'm taking 90% of it back off again.

If I feel that all blemishes seem to filled, my next coat is standard primer which is typically tougher than filler/primer. It doesn't sand as easily but I don't mind since I'm usually just smoothing it out at this point to get ready for paint.

Randy

(BTW, that's U-Pol UP2722 over a lightly glassed Big Bertha body tube. The glass layer is black because I like to tint the epoxy.)

 

[WizardOfBoz]

Randy, It's clear that you have more experience than I do - I'm gratified that I'm using a process that you've tired and found to be true. Rustoleum seems to work fine for me, though. It's Krylon that doesn't seem to cover well, and that oversprays a lot - I think I loose 70% of my paint to the wind. Did you say that you use Duplicolor?
Thanks

 

[SolarYellow]

I basically don't use Rustoleum anything. I'm sure they have some decent products nowadays but it seemed like any Rustoleum I tried in the past didn't work well for me.

My process is that I start with a heavy coat of filler/primer. Then, as you mention above, I look over the model and anything that the filler/primer won't hide gets dabbed with red Bondo spot putty. The Bondo works well because it dries fast and it has a similar "sandability" as the filler/primer. I then almost completely sand away the filler/primer/Bondo until only the areas that needed filling are left (see pic). That's why I like this layer to be very sandable. I'm taking 90% of it back off again.

If I feel that all blemishes seem to filled, my next coat is standard primer which is typically tougher than filler/primer. It doesn't sand as easily but I don't mind since I'm usually just smoothing it out at this point to get ready for paint.

Randy

(BTW, that's U-Pol UP2722 over a lightly glassed Big Bertha body tube. The glass layer is black because I like to tint the epoxy.)


View attachment 655428

I've found that when I go that far with the F/P over something tougher (even standard primer or polystyrene plastic) that the F/P, being softer, gets flatted/dished out more than the substrate. For the layer I want to be flat/final contoured, it needs to be mostly F/P with whatever is under it just barely showing.

 

[RCBrust]

It's Krylon that doesn't seem to cover well, and that oversprays a lot - I think I loose 70% of my paint to the wind. Did you say that you use Duplicolor?

Yeah, Krylon isn't what it used to be. 20 years ago Krylon was all that I used, but then they changed the formula. I've seen a lot of complaints about the newer Krylons. I believe that you can still get the original Krylon 5-ball lacquer under their industrial division but I haven't tried it yet. I like lacquer so I use Dupli-Color Perfect Match spray cans and also Tamiya spray cans. The Tamiya cans are kinda small but come in many colors. The Dupli-Color cans are larger but the color choices are fewer unless you're after a metallic. You can get your basic red, white, black, etc.

Randy

 

[SolarYellow]

https://www.zoro.com/ is the online face of Grainger and is my go-to for Krylon Acryli-Quik paint, or anything else from Krylon's industrial lines.

 

[manixFan]

Interesting results. I’ve been using Dupli-Color filler/primer my entire ’rocket career’ and I’ve never had an issue with it gumming up sandpaper, even when I sand it within an hour of using it.

But I always wet sand. That may be the difference.


Tony.

 

[RCBrust]

https://www.zoro.com/ is the online face of Grainger and is my go-to for Krylon Acryli-Quik paint, or anything else from Krylon's industrial lines.

Thanks for the link. Does Acryli-Quik perform like the old Krylon?

Randy

 

[SolarYellow]

It's pretty darned nice. I don't know how the old Krylon was, but the AQ is excellent overall.

The only problem I've had is blush (flat/fog surface) when trying to paint the same afternoon as a rainstorm in the soggy, hot, humid SE.

Colors are limited, so I'm going to gradually add more Ace Hardware brand paints, and have to move in the direction of enamels generally to keep everything mixable.

 

[Bruiser]

I too use the Rustoleum 2 in 1 filler/primer with excellant results. I also love the Krylon Acryli-Quik paints. They are my go to.

Where can this Rustoleum bonding primer be found? I'd like to try it on the nose cone of the new Nike Smoke.

I saw the Upol product line when I was at Autozone buying some dark blue duplicolor, Nice to know there is another option should my fav disappear.

-Bob

 

[WizardOfBoz]

I also love the Krylon Acryli-Quik paints. They are my go to.

Where can this Rustoleum bonding primer be found? I'd like to try it on the nose cone of the new Nike Smoke.

I'll try the AQ paints.

Rustoleum Universal Bonding Primer. I got it at lowes. I use it then sandable filling primer then a color coat. The Krylon goes all over but with sufficient coats it does end up looking good.

 

[Back_at_it]

I'll have to give this a shot. I've been using SEM High Build now for a few years and really like it but the price has increased recently and the cheapest I can find it is $16 per can.

I'll give this a shot.

 

[neil_w]

I normally use the Rusto filler/primer, which is OK but does need to dry for a while for optimum sandability. I did not love the Duplicolor when I tried it, for various reasons. Might just give that U-Pol stuff a try. A bit expensive but not bad if it really is better.

If anyone else tries it, please post experience here.

 

[SolarYellow]

Where can this Rustoleum bonding primer be found? I'd like to try it on the nose cone of the new Nike Smoke.

Krylon has a "Fusion" primer that is supposed to be specifically formulated to maximize adhesion to plastics.

The Rusto is white, which might be an advantage with light colors over it.
https://www.rustoleum.com/product-details/consumer-brands/auto/primers/universal-bonding-primer

Estes' NCs are all polystyrene AFAIK, and pretty much any decent primer should stick well. Make sure the first thing you do, before anything else, is wash them with dishwashing detergent (Dawn has a reputation for being the most effective) and warm water to remove the mold release film.

 

[Donnager]

If you want a filler for rockets, I'd look hard at Kilz. It's dusty as it can be but does a great job filling low points.

Duplicolor sandable filler primer is a close second, but If I want less dust, I go to Duplicolor.

 

[WizardOfBoz]

I've been using red glazing compound to good effect. Not sure it works great on the tube grooves but for smoothing out rough epoxy surfaces I like it. But you do end up with a lot of red dust!

 

[Titan II]

I've been using red glazing compound to good effect. Not sure it works great on the tube grooves but for smoothing out rough epoxy surfaces I like it. But you do end up with a lot of red dust!

Works great on grooves too.

 

[neil_w]

My reason for not using the Bondo stuff is simply that it stinks to high heaven. That is a non-starter in my house.

 

[bobbyg23]

Upol is great. Along with their paints.

 

[ksaves2]

I've not used it but make sure one uses the primer that goes with the color coat they intend to use or the color coat might bubble when spraying the clear coat.
I've sealed tube spirals with wood putty, sanded then painted with standard dope "sanding sealer" on cardboard tubes. Yeah adds weight but I could always use a higher impulse motor to fly! Was a good base to shoot primer and paint if I wanted to take the time to get a "glass finish".

 

[Donnager]

After the preference toward thick primer, my favorite for filling grooves and low spots is 3M Acryl green spot putty. It basically plays the same as the Bondo red, and, honestly, smells the same.

You probably won't be using it in the house.....unless you are single.

For smaller non FG stuff, I use the Elmer's CWF for most things.

 

[WizardOfBoz]

My reason for not using the Bondo stuff is simply that it stinks to high heaven. That is a non-starter in my house.

I just used bondo to fill in some minor grooves in a wood step I added to my basement. Two part Bondo does have a pungent odor.

The red glazing compound is one-part. Put it on, smooth it out, it dries pretty quickly and you can sand. There is an aroma but its not as strong as normal Bondo. I don't find it bad at all. But the red dust from sanding is... well, best done outside.

 

[WizardOfBoz]

After the preference toward thick primer, my favorite for filling grooves and low spots is 3M Acryl green spot putty. It basically plays the same as the Bondo red, and, honestly, smells the same.

Interesting. I'm biased toward 3M (I'm an engineer and have friends who've worked there) but still - Acryl White is about 30 bucks/tube and Bondo Red is 12.50/tube. But the Acryl tube is 14.5 ounces and the Bondo is 4.5 ounces. Given that its' white and probably is better under paint I will try Acryl. Thanks, @Donnager

 

[Donnager]

Interesting. I'm biased toward 3M (I'm an engineer and have friends who've worked there) but still - Acryl White is about 30 bucks/tube and Bondo Red is 12.50/tube. But the Acryl tube is 14.5 ounces and the Bondo is 4.5 ounces. Given that its' white and probably is better under paint I will try Acryl. Thanks, @Donnager

This is what I've been buying...https://www.amazon.com/gp/product/B004BZOTQQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

It is about $30 with prime shipping. It may last long enough for the dregs to be difficult to get out at the bottom of the tube, but it's far larger than the parts house bondo single stage red tubes.

Edit: Also, those red Bondo tubes aren't exactly "full".

 

[Back_at_it]

The best I've ever used out of a spray can that didn't require you to add harder is SEM high build. The costs have gone up over the past couple of years but I can still normally find this on line around $16.50 per can if I buy it in case quantity. Still seems expensive when compared to something like Rust-Oleum but you get what you pay for. This stuff is cured in an hour and can be sanded without clogging sandpaper. I also use a lot less of this as compared to Rust-Oleum brand. Two coats is generally enough.

I also like that it comes in different colors. Using the white primer for lighter colors is nice and gives a great base for neon colors.

https://semproducts.com/product/high-build-primer-surfacer/42013#product-details

 

[SolarYellow]

Ace gets their own SKU of this product, but from what I can tell, it's identical to the versions sold elsewhere. It's catalyzed, but there are posts about it sanding really nicely.

https://www.acehardware.com/departm...ools-and-maintenance/auto-body-repair/8065377

 

[SolarYellow]

The best I've ever used out of a spray can that didn't require you to add harder is SEM high build. The costs have gone up over the past couple of years but I can still normally find this on line around $16.50 per can if I buy it in case quantity. Still seems expensive when compared to something like Rust-Oleum but you get what you pay for. This stuff is cured in an hour and can be sanded without clogging sandpaper. I also use a lot less of this as compared to Rust-Oleum brand. Two coats is generally enough.

I also like that it comes in different colors. Using the white primer for lighter colors is nice and gives a great base for neon colors.

https://semproducts.com/product/high-build-primer-surfacer/42013#product-details

Where do you find cases of that? I looked around and found only single cans for ~20.##/ea.

 

[Back_at_it]

My last order came from Houseof1000Kolors. I paid $16.58 per can and bought a full case of 6 cans. That was back in March of this year.

If you have a Finish Masters automotive paint store local to you, talk to them. They have had the lowest prices I've ever paid but they don't always have it in stock.