SEARCH SCALEAUTOMAG.COM

Enter keywords or a search phrase below:

How to Cover Puttied Seams

614 views
8 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    April 2020
How to Cover Puttied Seams
Posted by Coreysan on Saturday, April 18, 2020 12:03 AM

I have two white painted styrene pieces glued together quite well, and the seam is puttied with Tamiya white putty.

However, when I applied white primer and white base coat several times, I can still see the putty. Its obvious.

Are there any tips out there for doing a better job at covering puttied seams?

So far my tests have all been with rattle cans. I haven't tried airbrushing yet because the parts were already previously painted with rattle cans, so I 'm trying to keep everything matched.

Any thoughts, tips, secrets, or advice?

Tags: putty , seam
  • Member since
    January 2005
  • From: Canberra, Australia
Posted by aussiemuscle308 on Saturday, May 2, 2020 5:54 AM
hopefully some better modelers will chime in, but i think i've just sealed the putty with urethane paint or cyanoacrylate glue (super glue)

My Flickr: https://www.flickr.com/photos/87459383@N07/albums

  • Member since
    January 2013
  • From: Sugar Land, Texas, USA
Posted by VintageRPM on Saturday, May 2, 2020 4:49 PM

Hard to say without seeing the seam, but I suspect it needs to be reputtied and/or resanded out. Many potties will shrink as they dry, so it can actually take 2 applications to get it right. (Or overfill the first time and sand it back.)

  • Member since
    August 2015
  • From: Hamptonville, NC
Posted by TarheelRick on Sunday, May 3, 2020 7:32 AM

Some of the "model putties" we use are a bit porous when dried.  It may not be visible to the naked eye, but the porosity is there.  When you paint, the paint seeps into those pores and causes that seam to remain visible.  Sometimes a primer-sealer will take care of this problem.  Another option would be to switch to another type filler such as Evercoat, Bondo glaze filler, or something similar.  They have a different chemical make-up and normally do not ghost.  One other option that I use occasionally is acrylic nail filler, found in most cosmetic sections of the big-box stores.  It works very well for small spots or large recontours, is quite resilient to cracking when sanding, but is susceptible to excess heat such as in a dehydrator.  Hope this helps.

I build models because I can't afford the real thing!

  • Member since
    December 2003
  • From: Nova Scotia
Posted by Bainford on Wednesday, May 6, 2020 12:22 PM

TarheelRick

Some of the "model putties" we use are a bit porous when dried.  It may not be visible to the naked eye, but the porosity is there.  When you paint, the paint seeps into those pores and causes that seam to remain visible.  Sometimes a primer-sealer will take care of this problem.  

I found this to be a problem, too. Especially bad in the years before I used primer under my paint. Primer helps quite a bit.

When doing body work with solvent based putty, I give it lots of time after application to let it cure and shrink. When the putty initially dries, sanding off the outer surface or 'crust' will speed up the curing/shrinking. After sanding smooth, a second application may still be needed. Or, using a two-part catalizing putty will virtually eliminate shrinkage.

After the putty has been sanded smooth, I apply a coat of Gunze Sangyo Mr Surfacer (a brush on lacquer primer) over the puttied area to act as a sealer. Let this dry (and shrink), then wet sand smooth with 1000 or 1500 grit paper. Use a block sanding technique whenever you can. This stuff sands beautifully smooth and feathers out perfectly. The stuff is also excellent for repairing panel scriber slips.

Be sure to primer after any body work using putty.

"It would be unusual, if the unusual didn't occur."

- Steamboat Gariepy

Trevor

  • Member since
    February 2008
  • From: Seattle, WA
Posted by gbk1 on Wednesday, May 6, 2020 2:40 PM

The problem of seams or bodywork joining points showing despite all our efforts to to sand them smooth and level with the surrounding surfaces can often be attributed to different shrinking rates and textures between the main surrounding surfaces and whatever we've used to fill the seam. The most extreme version of this, IMHO, because initially we are often convinced we did a perfect job of sanding and smoothing, is "ghosting". This occurs when, after the paint/primer/surfacer/putty combination we used to fill the indentation or seam reappears once the materials we used have cured and settled in to their stable state.

In my experience the best chance I have to avoid this problem is to use a "filler" that's as similar to the surrounding material as possible. For example when working with styrene I will fill the seam with styrene rod or strip, gluing the filler in place using a solvent adhesive like methylethylketone (MEK) or liquid cement. This welds the two materials together, and since they are both styrene, even if they may be slightly different formulation, they filled area will harden and cure at the same rate. Then I will sand the area so that it is level and the joint is as invisible as I can get it. I always wet sand. Finally I use a light finishing putty such as Tamiya White, applied sparingly and allowed to fully dry (with the Tamiya putty that's a good 12+ hours). Final finish sanding will eliminate any visible seam. If it doesn't on the first try - sometimes there are small surface irregularites still visible - a second light application will usually do the trick.

Even when I've done a simple butt joint, such as across the roof of a chopped top, and thoroughly joined the seam I will still run a bead of thin styrene rod down the joint and sand it smooth. This generally will totally eliminate any future ghosting.

For resin, modelers often use a mixture of superglue (Cyanoacrylate or CA) and talcum powder, often with excellent results. Many modelers report that using straight CA results in a cured filler that is too hard to sand down completely. To avoid this they either sand while the CA is hard but not fully cured, or they use the paste or putty mixture I mentioned above. For styrene some modelers will use the same technique but the filler they use is styrene sprue dissolved in MEK or liquid cement.

In my case I am highly allergic to CA and cannot use it at all. So for resin I use 5-minute epoxy as my final filler, first filling any gaps with styrene rod or strip glued in place with the epoxy and sanded smooth. Once the epoxy is fully cured (I allow 12 hours) I can sand it smooth and no future "ghosting" occurs.

If you want a perfectly smooth even continuous surface, here's a final finishing trick a friend of mine uses with exceptional results. Once you done your bodywork, but before doing your final priming and painting, paint your body with a good quality lacquer paint and let it cure completely. Then do your final finish sanding. My friend who taught me this technique  gets  spectacular show quality paint jobs after doing massive amounts of cutting and filling bodywork such as chopping, sectioning, recontouring, and wedge-cuts. He's absolutely obsessive about it but swears by it to get the results he desires. He will apply several coats of an approriately colored lacquer given the final color coats he antipates using and then allow them to dry for as much as 2 weeks before finish sanding using grits all the way out 2000. He then applies his final finish primer and color coats and clear, being careful to sand between coats. As I say, the results are spectacular and he NEVER gets ghosting. The few times I've had the self discipline to use his methods my results have been nearly as good. But I do consider this technique optional because it takes so much patience.... LOL.

Bernard Kron Keep On Buildin'

  • Member since
    April 2020
Posted by 58volvoV8 on Wednesday, May 6, 2020 4:47 PM

not the best answer but really you only hide the seems 1 out of 10 times you use putty.....i really only use it if the seem is bad enough that it will look worse than wavy putty....ive overglued with super glue gel on purpose to give something to sand....but usually I try to scrape unputtied engine block seems with a knife as smooth as possible then paint

  • Member since
    June 2012
Posted by jhande on Wednesday, May 6, 2020 5:42 PM

I've never used Tamiya putty, I have always used 3M Acryl-Green or Red since that's what I use on real cars.

With that said I always spread a "thin" layer then wet sand down to 400 grit. Apply a second coat if needed then repeat sanding. Sometimes I'll even sand with 800 grit. It is importand to allow putty to fully cure before sanding.

Once the putty is cured and sanded I'll apply a thin layer of primer/sealer, consitrating on the puttied area.

I then give it another light wet sanding before my finish coat.

Never had any problems.

  • Member since
    February 2008
  • From: Seattle, WA
Posted by gbk1 on Wednesday, May 6, 2020 10:19 PM

jhande

I've never used Tamiya putty, I have always used 3M Acryl-Green or Red since that's what I use on real cars.

With that said I always spread a "thin" layer then wet sand down to 400 grit. Apply a second coat if needed then repeat sanding. Sometimes I'll even sand with 800 grit. It is importand to allow putty to fully cure before sanding.

Once the putty is cured and sanded I'll apply a thin layer of primer/sealer, consitrating on the puttied area.

I then give it another light wet sanding before my finish coat.

Never had any problems.

 

Tamiya White is a "finish" putty. It's not meant to be used for building up surfaces, just as a final surface filler.

You mention Primer/Sealer and I forgot to include it in my write up. I find a final finish coat of primer sealer, wet sanded very smooth the way you describe, provides the proper surface for a smooth, glossy color and clear sequence.

Bernard Kron Keep On Buildin'

JOIN OUR COMMUNITY!

Our community is FREE to join. To participate you must either login or register for an account.

SEARCH FORUMS

FREE MONTHLY NEWSLETTER
By signing up you may also receive reader surveys and occasional special offers. We do not sell, rent or trade our email lists. View our privacy policy