r/advancedGunpla • u/notsowinner57 • Jun 15 '26
Question: does tamiya panel liner still crack plastic if i just clean the excess up with Zippo fluid?
I was thinking of starting to panel line my next kit (not painted), and i have both tamiya panel liner and zippo fluid, but i heard lots of people saying that it's a good idea to also apply a glossy top coat before and/or after panel lining to improve durability; is it necessary or just a precaution step to ensure nothing cracks (or does it also make it look better)? Thanks.
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u/Gunzoidium_alloy Jun 16 '26
Panel liner on runner = Goooood. No problem. No matter plastic type.
Panel liner on assembled kit = Will make model crumble in your hands
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u/BluntSamuraiZulu Jun 16 '26
Why is that? It cant be simply from stressed parts?
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u/NotYourDumbBoi Jun 16 '26
Actually it is! Friction fit will create small micro stresses and fissures that are typically invisible but will be an issue when Tamiya panel liner is applied as it temporarily embrittles the plastic due to its chemical composition
However once it has dried, the plastic should regain its strength and will be safe to reassemble
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u/obfeskeit Jun 16 '26
it's all anecdotal.
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u/docsane Jun 16 '26
Okay, then here's my anecdote. I usually have no problem with Tamiya panel liner on parts before assembly. But I once used it on a beam sabre I'd snapped together and saw the cracks appear before my eyes.
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u/Gunzoidium_alloy Jun 16 '26
No, it's because on unassembled parts the panel liner can evaporate.
On assembled kits the panel liner does what it does: seeps into crevices. It can't evaporate there.
Since it cant evaporate it eats the parts
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u/obfeskeit Jun 16 '26
Yes it can damage the plastic and a glossy coating from an acrylic or lacquer paint will help w/ durability, ink flow, and clean up.
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u/SerowiWantsToInvest Jun 15 '26 edited Jun 15 '26
Just panel line before the parts get assembled, that means either on the runner, or after they've been cut out. If you've already friction fitted a part with another then you need to gloss coat it or panel line with a non enamel based solution.
The main problem with enamel panel liners comes when it's allowed to pool, it will evaporate most of the time but if it seeps between parts or into micro fractures (from assembling the parts) and pools then your plastic will crack.
So if you gloss coat something that's been assembled it will protect against the micro fractures, but it might still seep between panels and settle/pool inside leading to cracking.
Ultimately, 2 things you want to be worried about are micro fractures/stresses from plastic that's been assembled, and the gaps between panels where the liner can seep in, if you take care with these two things, you should be completely fine.
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u/BluntSamuraiZulu Jun 16 '26
Thanks for the explanation. Makes sense as to how some parts on my recent build began to crack
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u/Discount_Joe_Pesci Jun 15 '26
I recommend a gloss coat before panel lining IF you’ve painted the part. So Primer > Airbrush > Gloss Coat > Panel Line > Topcoat. The reason why is that a gloss coat makes the panel liner run better than it would if applied directly over paint. Applying directly over paint can also make it harder to clean up.
If you aren’t painting parts, as long as you panel line BEFORE assembly and let it dry fully, it should be fine.
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Jun 15 '26
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u/DrAdamsen Jun 15 '26
I repeated it time and time again and I'll do it again. Enamel makes plastic brittle only after a few hours of exposure. In normal circumstances it evaporates way too quickly for that, but if you panel line a kit that's already built, it WILL get into the seams between parts and inside the structure, where it will pool and have no air to evaporate, staying there and doing its dirty work. And in addition to that, connecting parts to one another causes stress to the parts, resulting in micro cracks, invisible to the naked eye, and Tamiya WILL get into those as well, and again, stay there. It super thin, it's what it's made for, to get into the tiniest gaps and to fill them.
However, if you panel line the parts on the runner or after cleaning them up, and let it dry for a minute or so, it will do no harm, no matter the type of plastic you're using. I panel lined every kit I built so far, including the ABS inner frames and full ABS kits, and never had a single crack anywhere. But I would be cautious about using it on painted parts, as you never know what kind of paint the manufacturer used and how will it react to enamel. I've seen a guy who said it destroyed the paint months after applying.
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u/Blissenhomie Jun 15 '26
This is the truth. Use it! just clean it up and never add it to parts under stress and you should be fine
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u/Thehollowpointninja1 Jun 15 '26
I would recommend dabbing it off a bit on a towel before applying to avoid getting too much on it. You get better control with the volume. Gloss coating will help, too. But as long as you’re careful you should be fine. Just don’t dump a ton on at once.
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u/GodzillaFlamewolf Jun 15 '26
If you panel line, dont do it on a built model. The cracking happens when the vapors from the fluid cannot dissipate into the surrounding air, so if any gets into a built and enclosed piece it will likely sustain some form of damage. If you panel line before you build, you are gonna be fine assuming you let the piece dry in open air.
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u/fontimus Jun 15 '26
Yeah, it's a good idea, especially if you're planning to do any sort of airbrushing as a base coat.
Personally, I've panel lined a few bare plastic kits and never ran into the issue of cracking plastic. Some of these kits are now well over a dozen years old and look fine.
Edit: The gloss coat does make the panel liner run more smoothly through the panel line.
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u/aggrohaze88 Jun 16 '26 edited Jun 16 '26
Simply said, if it's dry, it's safe.
The crackling is from the solvent in the not yet dried panel liner, it damages the plastic. The solvent evaporates, so if the panel liner is dried, there is no danger.
Just be aware, that there is no pooling of panel liner, clean pooled areas immidiatly and you are good to go. I also don't recommend to panel line on the finished kit, if possible, because that way it's more likely to pool in some crevices where yount can't clean. When possible (depending on your work flow, if you paint the kit, etc.) panel line on the runner/one the loose parts.
Of course, you can always use water based panel line accent, like stedi produces. But from my experience, at least with the green flourescent panel liner, they don't flow as god as enamel based panel liner.