Masking tape messed up paint.

[papaof2]

Need suggestions. Building Tamiya Nissan R390 race car. Painted body Tamiya X7 Gloss Black yesterday and had in dehydrator all night. Masked off and painted X7 Red this morning. In dehydrator for an hour and removed masking tape to find tape has imprinted on paint. Two options, spray with clear, decal and respray clear, or decal and then spray clear. Or if there's other ideas I'm open to suggestion

Thanks
Curtis

 

[Belugawrx]

Wet sand the texture out gently with 1000 grit wet/dry sandpaper then clear/decal/clear

 

[Littlemarten]

What masking tape did you use?

To avoid this in the future:

Never put a masked model in the dehydrator. The prolonged heat, even if mild, will melt itself into the underlying paint, especially if it's gloss, and even more so with Tamiya or Gunze (alcohol solvent) gloss. Apply the paint, let dry to tack-free, then remove the masking before placing it in the dehydrator. You may also have cured the black paint too fast. For long cure times, reduce heat.

I don't think Tamiya or Gunze gloss paints have changed formulation since I last encountered surface problems with them. The problem lies in the gloss, which has (or at least had) a silicone compound that migrates to the surface as the paint cures. Produces a marvelous finish, but can produce problems with masking and paints applied to the gloss surface. What I recommended back then was to use a flat color for the base coat, polish it, then apply the gloss paint over that, and finally apply a clear Tamiya gloss over all. The Tamiya gloss avoids incompatibility issues with the underlying Tamiya paint.

 

[urumomo]

I don't think Tamiya or Gunze gloss paints have changed formulation since I last encountered surface problems with them. The problem lies in the gloss, which has (or at least had) a silicone compound that migrates to the surface as the paint cures.

silicone in an acrylic paint ?

 

[Littlemarten]

silicone in an acrylic paint ?

Not silicone per se, a silicone, or silicone-like compound. I'm sure the actual chemistry is a closely guarded trade secret.

Some folks in an IPMS chapter I once attended had a problem with paint applied over cured Tamiya. It was forming patterns of cracks like those seen in some drying muds. This is generally called "alligatoring" or crazing, and is caused by a defect called, appropriately enough, crawling. This happens when the overlying paint is poorly bonded to the underlying layer. All polymeric paints shrink as they cure. (True lacquers have negligible shrinkage.) When the bond to the substrate is poor, they crack. In severe cases, they also peel.

 

[urumomo]

what is a " silicone-like compound " ?

 

[Littlemarten]

what is a " silicone-like compound " ?

Like I said, I'm sure the actual nature of the thing is a closely guarded secret. It could be anything that contains portions of the silicone molecule, or it could be something entirely different with similar properties.

 

[urumomo]

I'm going with it doesn't exist

 

[papaof2]

Thank you Littlemarten. My plan is a light scuffing to smooth it out then spray with clear. If it's OK I'll decal and spray clear again. The chassis is beautiful so I strive on.

Curtis

 

[Heavy 7]

Also, avoid the dehydrator and let the paint air dry. Don't be in such a hurry.
Pep

 

[Littlemarten]

Organic chemistry is not only stranger than you imagine, it gets stranger every day.

I'm going with it doesn't exist

Oh really?

Silicones can exist in various forms, and their chemical structure depends on the specific type and intended application. Here are some common compounds and types of silicones:

Siloxanes: The fundamental components of silicones are siloxanes. They are composed of silicon and oxygen atoms arranged in an alternating pattern, with organic groups (like methyl, ethyl, or phenyl) joined to the silicon atoms. A siloxane's general formula is R2SiO, where R stands for an organic group.
Polydimethylsiloxane (PDMS): PDMS is one of the most widely used silicone compounds. It is a linear or branched polymer made up of repeating units of dimethylsiloxane (CH3)2SiO.
Silicone Resins: Silicone resins are three-dimensional networks of siloxane units, forming highly cross-linked structures.
Silicone Gels: Silicone gels are formed by cross-linking silicone fluids, creating a three-dimensional network with a gel-like consistency.
High Consistency Silicone Rubber (HCR): HCR is a type of silicone rubber with a high molecular weight, providing a thicker and more solid consistency.

For further information:
https://globalsilicones.org/explore-silicones/silicone-chemistry/
https://www.americanchemistry.com/chemistry-in-america/chemistries/silicones
https://en.wikipedia.org/wiki/Silicone

 

[urumomo]

None of that exists in that Tamiya or Gunze coatings .

 

[papaof2]

Saved it, scuffed with 3500 sanding pad and sprayed clear. Decaling and another clesrcoat in a few days.

 

[Littlemarten]

None of that exists in that Tamiya or Gunze coatings .

That isn't the point. There are more silicone compounds in the world today than you can shake a paint brush at. And I'm quite sure that neither company is telling what's in their product unless required by law.

 

[urumomo]

It's exactly the point .
It's the point you just made again .

 

[Belugawrx]

Nice job saving your paint....you'll need to come back and show us the finished build...man that is one beauty car and livery !!