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Paint problem

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  • Member since
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Paint problem
Posted by NVSRR on Sunday, March 29, 2020 10:54 PM

Well primer actually.      These were cleaned and let dry.  They are Kaslo shop shells.  The primer is Tamiya primer. What caused those craters to form?

I put two more coats on and it did level out a good number of them.   Can Tamyia be sanded with 600 grit wet dry?  That is assuming that what ever caused this doesnt wreck havoc with the paint. The most damage is on the hood and nose top.  the sides have some but not as bad.  The cat walks and porches have some but they should vanish into texture once painted.

The weather might have something to do with it.  rain and damp have been the theme for months.  more than normal. one or two days sun then more rain.  Could that be the cause?

 

Shane

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Posted by mbinsewi on Sunday, March 29, 2020 11:05 PM

They almost look like the bubbles you can get when pouring Envirotex water scenes.

Maybe there was something on the shell, like hand/skin oils?  I dunno? Maybe give Kaslo a call, and see what he thinks.

I don't see why you can't sand it with wet/dry paper.

I like the Horst filter.  I have a few coming.  

Mike.

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Posted by tstage on Sunday, March 29, 2020 11:17 PM

I always try and paint when the humidity is in the 40-60% range and the temps are between 65-80 degrees.  Some questions to ask:

  • Is your shell plastic?
  • What did you clean your shell with?
  • Did you touch the shell with your bare fingers after it dried?
  • What kind of base is your primer?  Acrylic?  Enamel?  Lacquer?
  • Did you spray the Tamiya in thick coats or thin coats?
  • How much dry time did you give between coats?

The primer looks fairly thick from your photo.  While it's always a good idea to prime metal shells, you really don't need to prime plastic shells.  And it's always best to spray in several thin coats than fewer heavier coats.  The primer/paint will dry quicker that way and will help minimize the risk of overspraying important detailing.

I clean my shells in warm (not hot) water & ivory soap and I use a toothbrush to gently scrub all surfaces.  I then rinse them in cool water and set them aside on a paper towel to dry.  (For speeding up the drying process I sometimes use filtered compressed air.)  My final cleaning regimen is to swish the shell in 99% isopropyl alcohol for 10-15 seconds then let it air dry in a clean area.

Once the above is done I only touch the shell using flat tweezers so that I do not re-introduce oils from my hand onto the shell again.  (Powder-free gloves would work also.)  I also use paper grocery bags as my spraypainting and drying platform.

Tom

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Posted by SeeYou190 on Monday, March 30, 2020 1:57 AM

That really looks like there were droplets of oil on the shell. That does not look like human finger oil.

-Kevin

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Posted by rrinker on Monday, March 30, 2020 8:01 AM

 You can see the stain coming through around some of the holes - definitely something on the shell prior to the paint hitting it. 

                           --Randy

 


Modeling the Reading Railroad in the 1950's

 

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Posted by NVSRR on Monday, March 30, 2020 8:52 AM

The shell is a resin with lots of etch metal parts, white metal, and another casting resin and plastic.   

same process for cleaning is water and dish soap and tooth brush.  All my models get this prior to paint.  I have done other kaslo locos and other resin base shells with no problem like this

 

the shells got put right onto the supports that hold them painting   So i dont have to touch them

I am not sure what solvent type tamiya is.  Definitely not laquer though.

usually only need one coat.  The other two were put on after the pic to try to soften this first coat and get it to flatten out.   That did work to a point. The pic was done after an hour of dry time when i found the problem with the first coat.

 

i noticed how thick it looked. But it never hides or obscures detail.  It seams to thin out over 24 hours as it cures and off gasses. 

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

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Posted by NVSRR on Monday, March 30, 2020 8:54 AM

They sat over night for drying too

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

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Posted by Mark R. on Monday, March 30, 2020 9:16 AM

Judging by the larger picture, looks to be a thick coat that skinned before the underlying finish gassed off, forcing tiny bubbles to break through the surface. You can see the gray is darker around the bubbles indicating uncured paint below the surface.

Tamiya FSP does go on rather thick when applied properly, but settles in quite nicely once cured. A cooler environment works best for that paint. Do not try to accelerate the drying time with heat - that will result in what is shown. Let it gas off naturally for 12 to 24 hours.

Painted dozens of engines with that primer and never had a problem.

Mark.

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Posted by RR_Mel on Monday, March 30, 2020 10:32 AM

I’ve had that happen to a resin casting, looked like your picture.  Tried striping and repainting it twice with the same results.  I was using solvent based paint.  It took Acrylic paint first try no problems.  My guess was something in the resin casting that the solvent paint didn’t like.
 
I’ve had similar problems when painting Zamak using solvent based paint but not using Acrylic paint.
 
 
Mel
 
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
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Posted by SeeYou190 on Monday, March 30, 2020 1:04 PM

NVSRR
The shell is resin.

OK, there we go.

I paint A LOT of resin models. Mostly these are wargaming vehicles made by Battlefront, Game Models Inc, or Forge World. I also build plenty of resin freight car kits from Funaros & Camerlengo, Westerfield, Yarmouth, and Sunshine Models.

After sporadic problems priming these ( I was getting "fisheyes", which is what it look like you have, but small ones), I began cleaning all of these castings with Brake And Parts Cleaner from the automotive section.

Washing in dish soap was not getting it done all the time.

The Brake And Parts Cleaner will somewhat attack and soften the resin. Do not touch it until it is dry, or you will imprint a depression into the casting. Use it outdoors only. The result is a perfectly clean casting that will paint well because the process gives the casting a bit of a "tooth" that will hold paint well.

Be careful, and this will solve your problem.

This UTAH BELT boxcar is a resin kit from Yarmouth models.

-Kevin

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Posted by Medina1128 on Wednesday, April 1, 2020 12:15 PM

After cleaning any model (warm water and Dawn detergent), it NEVER gets touched with bare hands. Wipe model down with tack cloth. This will remove any lint, hair, dust, etc. I blow off the model with air from the compressor. I then spray with 2 thin coats of primer (Krylon light gray). Check the model closely at this point to check for loose lint, hair, etc. CAREFULLY remove with tweezers. Mask, if needed, then paint. I use an airbrush because I can better control the amount of paint applied, as opposed to a rattle can.

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Posted by SeeYou190 on Wednesday, April 1, 2020 1:41 PM

Medina1128
Wipe model down with tack cloth.

DO NOT buy the Home Depot store brand (HDX I think) tack cloths. These are garbage and leave a sticky residue behind.

The Home Depot near me no longer carries brand name tack cloths. I now buy mine from the Sherwin Williams store, and they are good.

I hope this saves someone some grief.

-Kevin

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Posted by rrebell on Wednesday, April 1, 2020 2:48 PM

SeeYou190

 

 
Medina1128
Wipe model down with tack cloth.

 

DO NOT buy the Home Depot store brand (HDX I think) tack cloths. These are garbage and leave a sticky residue behind.

The Home Depot near me no longer carries brand name tack cloths. I now buy mine from the Sherwin Williams store, and they are good.

I hope this saves someone some grief.

-Kevin

 

The ones at HD were never ment for fine detail things.

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Posted by SeeYou190 on Wednesday, April 1, 2020 3:04 PM

rrebell
The ones at HD were never ment for fine detail things.

They are not good for anything in my experience. I used one on the MDF panels for my paint booth project, and they almost ruined my efforts. It was difficult to get the residue off of the surfaces. Thank heaven I did not try them on a model.

I would suggest everyone avoid this brand for any useage.

-Kevin

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Posted by Track fiddler on Wednesday, April 1, 2020 5:37 PM

Looks like a tough one to determine.

There's only one cause that made that happen but there's so many different variables that it could be.

Just a thought.  How old is your compressor and where has it been stored?  It could be a condensation problem.  Keyword could be but they look like tiny water droplets bubbling to the surface of the paint to me.

I used Tamiya paints only a few times with a brush but I know when I tried to clean the brush the paint was not water soluble.

This is on a bigger scale but it shouldn't matter.  I don't know much about mini compressors but it's the same Principle as a larger one.

I borrowed my Automotive spray gun to my friend Erv who was painting a hood from a junkyard for his truck.

When he sprayed the hood with primer it looked exactly like your locomotive after it dried.  Small round craters with an ever so slightly darker grey shade around the groups.

We found out there was condensation in his compressor.  After we drained his compressor filled it and blew it out a few times it turned out fine.

If you have a filter before your hose please disregard my thaughts.

 

 

TF

 

P.S.   I forgot to mention we did sand the darker areas completely down before we repainted.  Erv told me the trapped water would keep dissipating through the holes if we didn't.

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Posted by BigDaddy on Wednesday, April 1, 2020 5:45 PM

Track fiddler
It could be a condensation problem.

Condensation is a fact of life and physics, in compressors.  The larger ones have drain cocks, but the ones that included in an "airbrush kit" do not.


I added a water trap/regulator to my 5 gal compressor.  In less than a year it developed a large internal leak.   I threw it away and didn't have the problem since of it spitting water, like my little badger compressor did.

Henry

COB Potomac & Northern

Shenandoah Valley

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Posted by rodsaw on Wednesday, April 1, 2020 6:11 PM

Leave there and call it hail damage - it will become the rage.  Smile

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Posted by Track fiddler on Wednesday, April 1, 2020 6:19 PM

Interesting Henry.

A guy's got to remember to drain his compressor once in awhile.  I must admit I'm guilty of not doing it all the time and I didn't know the little ones do not have drain cocks.

I can't even remember the last time I used my compressor for painting though.  I would imagine the guys that use them for painting all the time, drain them every timeSmile, Wink & Grin

 

P.S.   I wonder if you can take those mini compressors,  tip them upside down and blast the water through the hose?

 

 

 

TF

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