Gesso as a filler primer?

[Marc_G]

Hi folks,

I'd heard a few folks here recently mention using Gesso as a sandable primer of sorts, so I'm starting a thread on the topic to collect experiences about application, sanding, paint compatibility, and so on.

I bought the Liquitex Gesso Surface Prep (product 5304) from Micheal's (had a gift card to use up!) and got a small bottle for about $8 before coupon.

Resembles white-out for typewriters, IMHO. I was thinking of painting it onto the fins and nose cone of my SEMROC Ranger (see thread in LPR). Let it dry overnight, sand down. The balsa has been sealed with CA so at this point I just want to fill the grain. I'm looking for something a bit smoother than CWF, without the fumes of spot putty. Normally I would CWF or putty, then hit with gray auto filler primer. Looking to eliminate the spray filler primer step if possible.

I'm interested to hear experiences before I go ahead and use it on my Ranger. It will be painted with acrylic airbrush paints, so I'm not too worried about compatibility as Gesso is designed for this. Mostly my questions are in terms of grain filling and sandability.

Thanks!

Marc

 

[Larry Curcio]

Hi folks,

I'd heard a few folks here recently mention using Gesso as a sandable primer of sorts, so I'm starting a thread on the topic to collect experiences about application, sanding, paint compatibility, and so on.

I bought the Liquitex Gesso Surface Prep (product 5304) from Micheal's (had a gift card to use up!) and got a small bottle for about $8 before coupon.

Resembles white-out for typewriters, IMHO. I was thinking of painting it onto the fins and nose cone of my SEMROC Ranger (see thread in LPR). Let it dry overnight, sand down. The balsa has been sealed with CA so at this point I just want to fill the grain. I'm looking for something a bit smoother than CWF, without the fumes of spot putty. Normally I would CWF or putty, then hit with gray auto filler primer. Looking to eliminate the spray filler primer step if possible.

I'm interested to hear experiences before I go ahead and use it on my Ranger. It will be painted with acrylic airbrush paints, so I'm not too worried about compatibility as Gesso is designed for this. Mostly my questions are in terms of grain filling and sandability.

Thanks!

Marc

Gesso is water-based. It can cause fins to warp. Haven't had the problem on plywood. It's also lessened if both sides of each fin are done at once.
Gesso is also a little heavy. (It's basically dilute plaster.)

Since you seem sensitive to fumes, it's worth noting that gesso makes rocket materials more compatible with acrylic paints. This, in fact, is why I've used it in the past. Now and then I get fed up with the toxic vapors.

-LarryC

 

[Marc_G]

Right about the warping, but since I usually seal with CA first I'm not worried about that part. I figured I'd put it on sealed fins and balsa NC, and maybe paint it over tube seams. Than sand down flat and give the whole bird a coat of "sealer white" by Createx (auto-air brand line). Then whatever I poor coats are needed.

 

[Marc_G]

I painted one fin of my Ranger (just one side of one fin, actually) with the Liquitex 5304 Gesso. Let it dry a couple hours. Sanded. It didn't sand well as the Gesso was a bit elastic. It wasn't terrible, just not optimal. Following a tip I found on an art forum, I'm going to try mixing in some joint compound or spackle to create something close to the much more expensive "Hard, Sandable Gesso" made by several vendors. These tend to have more calcium carbonate and or talc.

The experiment continues. I'm hoping to have a replacement for the spray auto filler primer when done. Note, I don't see this as a replacement for CWF... this is eventually going to take the place of the final finish primer, not the real grain filling of CWF. At least that's how I see it.

Marc

 

[mjennings]

Interested to see how things work out. I bought a bottle of Bob Ross Gesso a while back and hadn't had a chance to try it yet.

 

[mdoering]

I bought a bottle of Bob Ross Gesso a while back and hadn't had a chance to try it yet.

That should make for a happy little rocket

:rofl:

 

[Marc_G]

One amusing note:

Sometimes people on these forums get a bit uppity. But I think this well-curated forum is very gentle. Over on an art forum where I was researching the Gesso topic, one of the mods was ragging on a poster about using the term Gesso in relation to the Liquitex or Golden product sold as an acrylic prep material. He said something to the effect of "you realize the members of this forum look with disdain on the use of the term Gesso to describe products that are not true gessoes. Gesso is made with calcium carbonate or talc in an animal glue binder and acrylic products are NOT gessoes."

Duuude!

The OP was describing a product with the word Gesso IN THE OFFICIAL PRODUCT NAME. So these art folks (some of em anyway) are pretty hardcore!

You'd think they were arguing over something important like wood glue vs. Epoxy... :wink:

 

[Larry Curcio]

One amusing note:

Sometimes people on these forums get a bit uppity. But I think this well-curated forum is very gentle. Over on an art forum where I was researching the Gesso topic, one of the mods was ragging on a poster about using the term Gesso in relation to the Liquitex or Golden product sold as an acrylic prep material. He said something to the effect of "you realize the members of this forum look with disdain on the use of the term Gesso to describe products that are not true gessoes. Gesso is made with calcium carbonate or talc in an animal glue binder and acrylic products are NOT gessoes."

Duuude!

The OP was describing a product with the word Gesso IN THE OFFICIAL PRODUCT NAME. So these art folks (some of em anyway) are pretty hardcore!

You'd think they were arguing over something important like wood glue vs. Epoxy... :wink:

Disdain certainly doesn't enter into this matter. As a technical point, though, it helps to know exactly what we're dicussing. Gesso is actually an Italian word meaning gypsum or plaster. I thought that's what you meant, so my previous remarks might be irrelevant. Sorry if I added to the confusion.

-LarryC

 

[Marc_G]

No worries Larry! Apparently a specific term "gesso" (plaster with animal protein binder) has been co-opted by marketing folks and is now applied to a variety of products that accomplish the same basic task of canvas preparation. Damn their oily hides (oh, wait, I'm one of them)!

Anyway, the experiment is under way. I mixed a good dollop of spackle into a hefty squirt of Liquitex 5304 "Gesso" and mixed it around. There was no problem dispersing the spackle into the liquid medium. After mixing it to apparent uniformity, I painted on a medium coat directly onto the CA-sealed fins (including the fin side that previously got straight "Gesso" and was subsequently sanded.

It went on nice; these fins have fairly minimal grain (on the balsa scale) so I wouldn't have bothered with CWF. I would normally have gone straight to filler primer, hit with several heavy coats, and sanded smooth. Let's see how this thickened acrylic gesso (TAG filler?) performs.

 

[luke strawwalker]

Interested to see how things work out. I bought a bottle of Bob Ross Gesso a while back and hadn't had a chance to try it yet.

"Happy little rocket... in a happy little tree... there's a happy little squirrel that lives back in there, somewhere...

Remember... you can have ANYTHING you want, in your world... "

hehehe... I miss old Bob... he was just THE coolest... very relaxing... used to LOVE watching him paint... very soothing...

Later! OL JR

 

[Pat_B]

I used the Liquitex Gesso mixed with some white acrylic paint sprayed through my airbrush. The results were OK, but I thought it took awhile to dry. It has to be completely dry in order to be sandable and that took at least overnight. That's much longer than using FNF where it can be sanded in maybe 30 minutes. I'll experiment with it some more but didn't think it had any advantages over FNF except for perhaps when a rocket barely needs any filling on its surfaces and this mixture might work out.

 

[Marc_G]

The Liquitex Gesso plus Spackle was mostly pretty dry after a few hours so I took a quick shot at sanding it. Much better than the plain gesso sans spackle. I'll let it dry overnight and deal with it after work tomorrow, but it seemed pretty promising as an alternative to spray filler primer. Not only would it be cheaper (by several X), but no fumes, and can be done inside during the winter. Though to be fair, I've never had trouble spraying filler primer in the cold, though it does take several days to fully dry to proper sandability when it's cold out.

Marc

 

[Marc_G]

Based on the initial sanding test last night, I used my mixture on the nose cone of the ranger. I'll post pics tonight before and after sanding of the NC and rest of the fins.

 

[mjennings]

That should make for a happy little rocket:

It's scientifically proven that Happy Little Rockets Fly higher than sad rockets

 

[Marc_G]

I'll put pics in this later today (at the auto shop now), but it seemed to work out pretty well. The sanding was not too difficult, though not quite as easy as auto filler primer. The Spackle added to the Liquitex "gesso" cut the elastic factor of the material so it powdered up pretty well during sanding with 220 grit. Essentially no clogging of the grit. I used a sponge for the nose cone and mostly used sanding blocks on the fins (used sponge for the edges and fillet areas).

I think it's ready for "sealer white," but I have to glue in the motor mount and coupler first. I'll post before and after pics later on.

 

[Marc_G]

Here is the nose cone with dried spackle/gesso mix:



And the nose cone after being mostly sanded down:



You can see there are still a few pin holes but mostly the grain is filled and I can tell you it feels baby-butt smooth.
I still have a polish-sanding with a 320 sponge to do before hitting it with sealer white.

 

[Marc_G]

Here are some shots of the fins before and after: