Plank on Frame questions -- pls help

Treadhead · Post by **Treadhead** » Tue Jan 16, 2007 12:04 pm

I'm practicing what is for me something brand new. I built up a series of bulkheads from styrene and skinned them over with styrene strip. I covered the structure and it seemed to look pretty good. I sanded it down and puttied the seams between the strips.

It all went to hell when I gave it a shot of primer. The seams are showing still. It seems I can't get the putty to go into the seams between the slats.

One possible issue is that I used Squadron Green putty first. It went on grainy and the primer seems to absorb into the putty while remaining on the plastic -- giving it the slatted look. I've scooped out the green putty and gave the whole thing a coat of Bondo spot and glaze putty. I'm hoping that will do the trick.

Does anyone have any experience in this area? How do you manage to blend the strips -- what kind of putty do you use?

Thanks!

Kylwell · Post by **Kylwell** » Tue Jan 16, 2007 12:17 pm

SquadGreen both shrinks and cracks somewhat easily. White is better. Aves is perfered, Black CA wonderful.

You could try several heavy coats of primer then sand, it might support everything and fills the gaps and whatnot sufficiently.

ignatz · Post by **ignatz** » Tue Jan 16, 2007 1:09 pm

Try giving it a coat of epoxy putty instead. Squadron green shrinks a lot, and softens the styrene underneath. It's also fairly brittle, so if there's even a bit of flexing between your styrene planking, it'll crack. I would coarse sand the form, to give the epoxy some tooth, then apply the putty, and sand it down to shape after it has cured. It's best to slightly undersize the form to allow a bit of thickness in the putty. I've used several types of epoxy glue that works too, Duro (?) and Pacer that's basically a thinner, sticky epoxy, same as the 2 part epoxy glue in the double syringe that you can get at the hardware store.

PetarB · Post by **PetarB** » Tue Jan 16, 2007 3:57 pm

Mr Surfacer?

Darkov · Post by **Darkov** » Tue Jan 16, 2007 5:12 pm

Both squadron green and Bondo glazing putty shrink when sprayed with primer. I had this same issue myself once. What I was told is that I 1) I could just put another coat of bondo/squadron on and resand and reprime untill the seam is gone. 2) Use a acrylic primer. 3) Use Aves epoxy putty and not have to worry about shrinkage.

At the time I didn't have Aves

so I went with option 2. It worked well but I now fill almost all larger seams with Aves.....Awsome stuff.

Hope that helps

Pete

TREKKRIFFIC · Post by **TREKKRIFFIC** » Tue Jan 16, 2007 6:37 pm

Darkov wrote:Both squadron green and Bondo glazing putty shrink when sprayed with primer. I had this same issue myself once. What I was told is that I 1) I could just put another coat of bondo/squadron on and resand and reprime untill the seam is gone. 2) Use a acrylic primer. 3) Use Aves epoxy putty and not have to worry about shrinkage.

At the time I didn't have Aves so I went with option 2. It worked well but I now fill almost all larger seams with Aves.....Awsome stuff.

Hope that helps

Pete

I use the Tamiya epoxy putty; is that similar to Aves ?

Darkov · Post by **Darkov** » Tue Jan 16, 2007 7:44 pm

I've never personally used the Tamiya putty. But if it is like most epoxy putties it should have little to no shinkage.
Maybe someone who has used that putty will have a better answer for you.

I have used the 2 part plumbers putty before when I didn't have anything else available. That worked out really well...the stuff dries hard as a rock so you really want to make sure you don't over do it. Or you will be sanding for a while.

I have also had good results with Sig epoxolite. It is also a 2 part epoxy filler. It is very easy to use and tends to not be as hard as the plumbers epoxy. I picked that up at my LHS in the airplane section.

Pete

ignatz · Post by **ignatz** » Tue Jan 16, 2007 8:19 pm

It depends. If it's the silver grey contour putty, yeah. Same-ish as the Squadron Green, White, Red, and Bondo Spot Putty. Tamiya Polyester putty with the small tube of catalyst is a polyester epoxy putty and will function pretty much like Aves putty, Duro epoxy glue, or Mori Mory Putty. Very stable and strong stuff.

Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Tue Jan 16, 2007 8:28 pm

I usually go right to fiberglass and resin.
one layer of fiber glass, and two to three coats of resin.
Then sand and fill, and sand and fill and sand...

Vince Hoffmann · Post by **Vince Hoffmann** » Wed Jan 17, 2007 10:23 am

Umi_Ryuzuki wrote:I usually go right to fiberglass and resin.
one layer of fiber glass, and two to three coats of resin.
Then sand and fill, and sand and fill and sand...

Same here. 1 layer of 1.4oz (lightweight plain weave) fiberglass cloth and a couple applications of resin will solve your problems. You might want to consider a random orbital or finish sander to get a perfect finish.

Putty on wood won't give you very good results because the wood is softer and you'll end up sanding off more wood than putty.

Treadhead · Post by **Treadhead** » Thu Jan 18, 2007 11:42 am

Thanks guys!

The problem was the modeler. I didn't have the patience to sand, putty and re-prime. It's starting to come around now. This was a test piece to see if the overall scheme would work. I think it will.

I like the idea of Aves. I'll use this on the bigger gaps.

Again THANKS!!