Do any of you use these reformulated paints?

You have to stay in your lane, ….your first big no-no is mixing the solvents without knowing how they’ll react to one another……. . Lacquers & enamels don’t mix well!….well, ….not at all,…..if using a lacquer such as dullcoat by Testors, etc., over an enamel finish, the enamel has to be completely cured, by like days!!….and then the lacquer has to be applied very lightly as so it won’t attack the under lying base color. Practicing on scrap with your ingredients will tell you what you can, and can not get away with. Your crazing and spider checking is not the result of the underlying plastic, more than likely it’s your color coat being saturated with whatever you sprayed over it……who makes the shell you’re attempting to paint?…let’s see it in a picture, and maybe we can provide a remedy to save your project ……

Pat

The shell I am attempting to paint (black) is the clear plastic roof shell...(the one I had to strip).  This car is a European model made by Lima. I think they are still being made...not certain.  There is usually a complete series of Lima cars for sale on ebay.

Ok, so you just want to shoot the roof a simple satin black?….am I reading this right?….you’ve already cleaned up the mess and you’re ready to start over?….

Pat

Yes, I'm ready to shoot just the roof. Will mask the window panels.  The color would be a satin black or semi-gloss black.

Ok good, I’m glad you were able to get the piece cleaned back up, …..I’d recommend a one hit wonder on that plastic. SEM automotive products makes a true rattle can urethane in satin black that is a good product. I wouldn’t even bother with a primer coat. The SEM has fantastic hide, and great adhesion. So my suggestion to shoot that roof would be to mask off the areas you don’t want painted, lightly scuff the areas you do want painted, wipe the roof down with a barely damp rag of 91% alcohol ( one wipe, one direction only ) then paint the roof,…..shoot one light coat but be consistent, observe that coat and allow it to flash. Be sure nothing reacted. If good, lay down a medium wet coat, and allow that coat to flash. You may or may not have to do a third coat, but that’ll depend on your painting skills, ……one thing to add, get some scrap pieces and practice on them, not your workpiece, …..get the sheen, and finish you want before moving onto the finished product…..

Pat

You mentioned this paint is a urethane paint. Is that the same as polyurethane? 

Are you familiar with acrylic-lacquer?

There is an auto parts store near me that has the SEM Trim Black 39143 in stock.  I'll get a can and give  it a try.  I have another"problem"  roof that I need to "strip" and repaint.

Thank you for the info and instructions!!!

Tamiya makes paint specifically for plastic models.  The members of my model car club including myself use it with great success.

https://www.tamiyausa.com/shop/paints/?sort=new

@Rockyroad posted:

You mentioned this paint is a urethane paint. Is that the same as polyurethane?

Are you familiar with acrylic-lacquer?

There is an auto parts store near me that has the SEM Trim Black 39143 in stock.  I'll get a can and give  it a try.  I have another"problem"  roof that I need to "strip" and repaint.

Thank you for the info and instructions!!!

Yes, urethane, short for polyurethane…..so it’s not an enamel, or a lacquer,…both of which I despise, ….technically, I despise anything in a rattle can, but for a rattle can product, it can’t be beat …..plus the can is large, so it’ll paint quite a few projects ……..what’s up with the other roof you need to strip ….let’s see what you’re working with…..

Pat

I am familiar with all paint types in the chemical world,……acrylic anything = 🤮

Pat

The other roof I need to strip is just like the clear one in ther picture.  It has slight paint crazing and a rough a overall finish.  If I am successful with the one I'm attempting to paint, I'll use your suggested process on that one.

@Rockyroad posted:

The other roof I need to strip is just like the clear one in ther picture.  It has slight paint crazing and a rough a overall finish.  If I am successful with the one I'm attempting to paint, I'll use your suggested process on that one.

I do not know the composition of the plastic you are working on, so recommending a stripping process is going to be difficult. But whatever you decide, DO NOT use lacquer thinner to strip that roof!!….it will for sure attack it!!…let’s start with 91% Isopropyl  and see how that reacts to the plastic,……try wiping a small inconspicuous spot with the alcohol and see what the plastic does….some folks report great success soaking plastic components in 91% alcohol to remove paint, and not harm the underlying plastic,….again I don’t know the composition of the plastic you’re working with, so some trial & error may be necessary……do not attempt to paint over crazed and spider checked paint, ….the results will be ugly ……if the alcohol doesn’t harm the plastic, I’d soak the roof for a good while and see if this releases your first attempt…..the only thing I’d take into consideration is it looks as if the windows are part of the roof assembly, so after soaking, I would not attempt to wipe on the window areas, …I would flush with tap water first, and let the areas settle dry before attempting to wipe them clean for your reassembly process…….my fear would be the strong alcohol may leave streaks on the window glass portion, that would be unsightly after your repair …

Pat

I agree with CSXJOE, Tamiya paint is the way to go on rattle cans.  It has a very fine spray and dries fast with a smooth and glossy finish.  I've used automotive spray paints too but only plastic when I used a primer.  

This is the paint remover I used to strip the paint off the clear roof shell in my original photo.  It is a water based high alcohol  content product...comes in a gel or liquid. I used an old tooth brush to apply and scrub off the disolved paint. Then rinsed with water and washed with a drop of Dawn liquid dish soap.

@harmonyards posted:

so it’s not an enamel, or a lacquer,…both of which I despise,

Both of which I love, but, only that actually made for models. When using lacquers on plastic, a sealer is needed so that the paint doesn't attack the plastic. Enamels can be safely used over lacquer, but, not lacquer over enamel. And the cool thing about using an enamel over a lacquer to do detail work is that small touch-ups can be done with paint thinner and not harm the lacquer.
Being one that really misses the old Floquil line of paint, right now I am really liking MCW lacquer paint using their primer to undercoat and seal.

@Rockyroad posted:

This is the paint remover I used to strip the paint off the clear roof shell in my original photo.  It is a water based high alcohol  content product...comes in a gel or liquid. I used an old tooth brush to apply and scrub off the disolved paint. Then rinsed with water and washed with a drop of Dawn liquid dish soap.

That’s ideal perfect prep, only thing I’d do is to lightly mechanically scuff the area you want to paint…..I prefer gray scotchbrite ( fine) ……..if you have a clean uniform surface, that is abated, there is no need for primer with the product I suggested…..you can skip that step! ……..the SEM will bond forever on a lightly scuffed surface ….…gray scotchbrite done lightly is the equivalent to 800-1000 grit. The SEM product will easily hide 600 scratches, so your finish will turn out super smooth and a very rich satin luster……

Pat

Thanks Pat for the "grit" info.  I have 800 + grit sand paper.  Thought I would wet-sand with 800 to start with and then determine where to go from there if needed.

Bought a can of ZEM 39143 today at O'Rielly auto parts...time to get started!

@Rockyroad posted:

Thanks Pat for the "grit" info.  I have 800 + grit sand paper.  Thought I would wet-sand with 800 to start with and then determine where to go from there if needed.

Bought a can of ZEM 39143 today at O'Rielly auto parts...time to get started!

Practice makes perfect,…..test on some scrap, or dead cars or parts …..

Pat

Just finished spraying the roof.  The prep was roughing/wet sanding the surface with #800 sand paper...washing with a dab of dawn dish detergent...rinsed...let dry.  Before spraying I wipe the surface with a damp cloth of isopropal alcohol...let dry.

Lightly sprayed the roof three times...each time was 5 minutes apart.  The spray can was helded 6"-8" from the roof surface (measured distance before spraying).  The results is shown below.  Even coverage with light, even crazing. I will let this painting session cure for a week befor attempting to spray it again...hoping the current painting will act as a barrier and result in a smoother finish.

I'm not sure what type of plastic the roof is made of, but I'm begining to believe any solvent based paint is not a friend of plastic.

@Rockyroad posted:

Just finished spraying the roof.  The prep was roughing/wet sanding the surface with #800 sand paper...washing with a dab of dawn dish detergent...rinsed...let dry.  Before spraying I wipe the surface with a damp cloth of isopropal alcohol...let dry.

Lightly sprayed the roof three times...each time was 5 minutes apart.  The spray can was helded 6"-8" from the roof surface (measured distance before spraying).  The results is shown below.  Even coverage with light, even crazing. I will let this painting session cure for a week befor attempting to spray it again...hoping the current painting will act as a barrier and result in a smoother finish.

I'm not sure what type of plastic the roof is made of, but I'm begining to believe any solvent based paint is not a friend of plastic.

I’ve never seen plastic react like that to urethane…..god only knows what kind of plastic they’re using ….. maybe contact the company that produces them and find out before attempting …..apparently we’re making a mess out of this project ….push come to shove, send me the **** things and I’ll get them to take paint!…it won’t be from a can, I can promise you that!…😉

Pat

Pat,

Theoretically, wouldn't letting this current coat cure (harden) for a week act as a protective barrier?  I could then shoot another light coat of SEM.

Push-come-to-shove I could just leave it as is.  From a distance it's acceptable (sort-of). 

@Rockyroad posted:

Pat,

Theoretically, wouldn't letting this current coat cure (harden) for a week act as a protective barrier?  I could then shoot another light coat of SEM.

Push-come-to-shove I could just leave it as is.  From a distance it's acceptable (sort-of).

In theory yes, …but this thing defies logic, …..I’d agree …..let it cure out, wet sand with 1000 or finer and try a reshoot ……..

Sort of is the same as almost, and almost only counts in horseshoes & hand grenades,….

Pat

Should have used a sealer!

@Big Jim posted:

Should have used a sealer!

Shoulda people are easy to come by!…..so what super sealer would you guarantee not to attack whatever odd form of plastic the OP is up against?….

urethane is the most forgiving of solvent based paints, clearly he’s had an issue with it as well,…

it may not be whatever form of product being used, it very well could be the propellants in the can doing the nasty deed…..sealer in a spray can has some sort of propellant in it as well,….something is attacking this plastic, …..I’d suggest the OP find out what he’s working with, ….not a bunch of shoulda done this, shoulda done that, ….

Pat

@harmonyards posted:

Shoulda people are easy to come by!…..so what super sealer would you guarantee not to attack whatever odd form of plastic the OP is up against?….

urethane is the most forgiving of solvent based paints, clearly he’s had an issue with it as well,…

it may not be whatever form of product being used, it very well could be the propellants in the can doing the nasty deed…..sealer in a spray can has some sort of propellant in it as well,….something is attacking this plastic, …..I’d suggest the OP find out what he’s working with, ….not a bunch of shoulda done this, shoulda done that, ….

Pat

I would recommend MCW 1004 Light Grey Primer. It worked great on my latest two paint jobs on plastic models where I used MCW lacquer paint. I have also used a sealer that was made by Scalecoat, but, don't know if it is still made. The best ever was Floquil "Barrier", which I know isn't made anymore, but, I still have a few bottles of.
Another piece of advice is to quit being a cheap-skate and get away from those "Hardware Store" paints! They are too much of a risk!
All of this could have been prevented if he had used a good model enamel in the first place!

My model was made by LIMA. LIMA was a 50 year old Italian company that went out of business in 2004. They made a lot of models for A.H.M.,Model Power, Rivarossi and others. So, LIMA could have used any number of plastic types used over that perid of time...no way of knowing for sure. Doesn't feel like an ABS like I first thought...more softer like some kind of styrene.

@Rockyroad posted:

The shell I am attempting to paint (black) is the clear plastic roof shell...(the one I had to strip).  This car is a European model made by Lima. I think they are still being made...not certain.  There is usually a complete series of Lima cars for sale on ebay.

The forum software does not allow a posted photo to be enlarged so the following question.

That looks like a Deutches Bundesbahn first class carriage. I have several other DB coaches along with a couple of SBB (Swiss) and SNCF (French) versions. They do make up into a nice, colorful train.

Most acrylic floor finishes can be used as a barrier coat on plastic.  Mix them at least twice as strong as the instructions on the bottle. You can use it full strength however it will leave a thicker coat and may obscure details. Plus it takes much longer to dry.  I prefer to spray but you can dip your item in it and allow to air dry. Just make sure to prop them in a manner that allows the excess to run off without the model sitting in a puddle.  If you want to remove it household ammonia takes it off.  I used to coat my eyeglasses with it to prevent the viewfinders on cameras from scratching the lenses of my glasses.  If it gets scratched strip it off with ammonia and recoat.  It will even cover light scratches on your glasses.  Lower anything you want to coat carefully so as not to create bubbles.  When removing, slowly lift one edge and let the liquid sheet off as you remove your item. SLOWLY ! Whether it be your eyeglasses or a model.  Another use. Used full strength I use it to glue traces down on PC boards it is somewhat heat resistant. More so than cyanoacrylate. Once I have a trace secured and fully dry I often add another coat over the trace and first coat to lock it in.   SWAG: That clear plastic roof & windows may be cellulose acetate. Cheap !  Just a guess.              j

Great information !!!

Thank you all for sharing your experiences !!!

CB&Q Bill

'Welp'...time to end this project.  Shot an new coat of SEM over the old coat...using the old coat as a barrier after letting it cure for 5 days.  This new coat went on evenly...no runs, etc........but.....same rough, evenly, crazed results.   I need to stop "now" before I destroy the roof.   The SEM paint resulted in the same finish as the Krylon Colormaxx.   I have to agree with Pat that it is not the type of paint (lacquer, enamel, urethane) but the solvent propellants.

Thanks for all the suggestions and step-by-step guidance to alwho responded to this posting