Acrylic paint lifting when masking

[walkerccw]

I am using Model Master Acrylic and hand painting.  I clean the plastic before I paint. I have used primer and no primer.

 

I currently have 2 kits I am working on.  Both were painted and let dry for 48 hours.  Today I masked them both with Tamiya tape and both kits the paint lifted off.

I have read a lot of information here and other sites and nothing seems to work.  Both of the kits are very old (Matchbox and Frog) from the 60/70's.  Does the age of the plastic have anything to do with it?

 

I need help bad before I toss them in the trash.

 

Thanks,

CCW

[Scott Hemsley]

What do you use as a primer?  I've always used a neutral coloured flat enamel (I primarily use MM enamels anyways) to give something for the acrylic to byte, whenever I've used acrylic paints.

 

Scott

Edited September 22, 2016 by Scott Hemsley

[JackG]

I have had this problem now and then, and that is with airbrushing acrylics.  Could it be the paint wasn't mixed well enough, or thinned too much and made it weak?

 

Scott has a good idea there, enamel primer would be much more resilient than an acrylic based one.

 

A couple other suggestions, try adding a clear coat before masking.  Also,  lose some of the tackiness of the tape, though there isn't a whole lot to begin with.  Before applying, put the strips of tape on the back of your hand, then peel and stick.

 

regards,

Jack

[Dances With Wolves]

27 minutes ago, walkerccw said:

I am using Model Master Acrylic and hand painting.  I clean the plastic before I paint. I have used primer and no primer.

 

Thanks,

CCW

 

When you say you 'clean the plastic', what does that entail exactly'? In tandem with that, are you getting the primer lifting too when you use it?

 

Thanks

 

Steve 

[walkerccw]

I have used Model Master Gray Acrylic Primer. I wash the kits in warm water/soap.I have built a few newer produced kits (Hobby Boss and Revell) and did not have the same issue.

 

I just remembered that I wiped the models with isopropyl alcohol and let dry before painting.

Edited September 22, 2016 by walkerccw

[Dances With Wolves]

1 minute ago, walkerccw said:

I have used Model Master Gray Acrylic Primer. I wash the kits in warm water/soap.I have built a few newer produced kits (Hobby Boss and Revell) and did not have the same issue.

 

I just remembered that I wiped the models with isopropyl alcoholo and let dry before painting.

 

Thanks - does that mean 'cooking' or lab grade Iso? The latter is 99.9% pure (and cleans thoroughly). 'Cooking' versions are adulterated with water I believe and purity is much less, effecting depth of cleansing and consequently, adhesion.

 

My m/o is Gunze or Tamiya acrylics, cut with cellulose (lacquer thinner in the US) - a 'hot' combo that etches to the plastic. Adhesion has never been a problem, even with aggressive tape adhesives. The only issues I've had were recently with test shots for Airfix where the plastic was injected in China but can't count this as production kits have never exhibited lift.

 

Different manufacturers seem to vary in whether mould release is evident or not but as my cleaning regime is solid, I don't get hit either way. I always wear latex free gloves at the painting stage, so as not to re-contamimate with skin oils after cleaning.

 

So has the MM primer lifted too and are you cleaning with lab grade Iso?

 

Thanks

 

Steve     

[walkerccw]

I am cleaning with 70% Iso.  The primer does lift.  Does the age of the kits/plastic matter?

[Dances With Wolves]

19 minutes ago, walkerccw said:

I am cleaning with 70% Iso.  The primer does lift.  Does the age of the kits/plastic matter?

 

Thanks for that - I know it may feel a bit tedious doing it but problems like this stand the best chance of cure when you've all salient facts to hand.

 

A modelling friend reported paint lift on a Revell 1/48 Tornado. Turns out he was using the '70% Iso' too. I asked him to switch to lab grade. Frankly, that extra 30% purity is key in maxing out adhesion - and wearing gloves.

 

Not sure on the age of the kit - again, if you're hitting the surface with lab grade Iso and an older kit is carrying more mould release on the surface, the lab grade will kill it anyway. I've not used MM paint but if it'll take Iso as a thinner then I'd use that over water - keeping it lab grade all the way of course. That's what I'd concentrate on trying first. By the way - do you always use gloves during / after cleaning to eliminate skin oils?

 

Beyond that, the advice to reduce tape tack will help either way but there's no doubt you can up adhesion in the mean time by swopping to lab grade Iso.

 

Wish you well with it mate.

 

Steve      

 

[Chuck1945]

My only experience with Model Master acrylics was a disaster and many years ago, so can't relate to the MM part of your problem. I do use acrylics though, mostly Tamiya (don't prime either) and mask with Tamiya tape. I used to rub down with 98% iso - while that always worked, it could also remove other acrylic paint previously applied   Testors has a cleaner, I think labeled Plastic Prep. That might help, but what I have be doing for the last few years is just scrubbing the assembled kit (prior to painting) with an old toothbrush and dishwashing liquid, rinsing thoroughly after.

 

 

[Dances With Wolves]

3 hours ago, Chuck1945 said:

I used to rub down with 98% iso - while that always worked, it could also remove other acrylic paint previously applied   

 

 

 

Hi Chuck:

 

I wasn't advocating rubbing down with IPA over a previously painted surface - just the bare plastic.

 

 

TTFN

 

Steve  

[Chuck1945]

10 minutes ago, Dances With Wolves said:

 

Hi Chuck:

 

I wasn't advocating rubbing down with IPA over a previously painted surface - just the bare plastic.

 

 

TTFN

 

Steve  

Steve,

I didn't think you were   I was simply mentioning that IPA can remove paint as well as whatever else may be on the plastic ... And IPA does dry faster than soap and water

[cossack52]

i always prime my kits with hycote acrylic spray cans.they do white,grey,red oxide,and also a white plastic primeras well as priming,they can prove useful in obtaining different shades and effects when applying the finish coats for removing paint i use flash power spray;doesn't harm plastic and is very effective

Edited September 23, 2016 by cossack52
addition

[Nick Millman]

I don't know enough about the type of plastics used by Matchbox or Frog but some plastics, e.g. ABS, absorb Isopropyl at the surface, causing a long term cycle limiting the life of the polymer. It sounds as though a chemical reaction between the type of plastic and Isopropyl has created a surface barrier to the acrylic primer.

 

I'd be inclined to lay off the Isopropyl completely and just use a mild detergent to wash the surface thoroughly. IIRC the Matchbox and Frog plastics are quite hard and glossy so it might help to lightly sand the surface if you can. 

 

Nick

[walkerccw]

Thanks for all of the suggestions. I will try a few different ones and let you all know how it turns out. I just got some 91% iso and will try that too.

 

My P-61 was almost finished, but when I masked the cowlings, that is where a lot of paint came off. I was just sitting here thinking how to remove all of the paint to start over. I used masking tape to pull the rest off!

[LaurieS]

Acrylic is just a coat of plastic. It relies on its strength in holding itself together around the plastic model. It does not stick well.

 

To provide a surface for the primer I use a wet and dry paper 1200 gauge. I keep the paper wet all the time. It ends

up with a very dull surface which is really scratched all over. This provides hooks for the primer to stick to. The scratches

are not discernible after applying the primer in any way.

 

I use Stynylerez Primer which can be applied by hand or airbrush. Adhesion is next to none among acrylic polyurethane primers.

It has many and more advantages than any other primer I have used.  Since I started using it I have had just one failure.

I took a chance did not wash or wet and dry. Wet and dried and re-applied to make good the poor area and it turned out perfectly.

 

www.badgerairbrush.com/PDF/STYNYLREZflyer.pdf  Comes up with a list. Open the first one where it says PDF

 

Laurie

 

 

[walkerccw]

This problem for me is so frustrating. I feel like I am ready to stop modelling.

I just had it happen again.  I have tried pre-washing the kit, wipe with iso 91%, allowing 48 hours to dry, primer or no primer.  The only things I haven't tried are sanding before I paint and trying some of the specialized primers listed here.

[LaurieS]

OK Walker "lets get serious".

 

Remove all paint so far.

 

1. Wash kit and make sure that you rinse well and get off all the washing liquid.

 

2. Get some 1000 gauge wet and dry paper. Cut a small piece 1.5 inches square.

Sand the plastic making sure the surface always is wet with water. This will give

a good sound base for the paint to grab on.

 

3. Rinse the plastic and dry.

 

4. With a soft brush dust to get rid of dust and hairs.

 

5. STYNYLREZ acrylics primer one coat.

 

6. You can also give the Stynylerez a light wet and dry as 2 above. any defects you can fill

and recoat the area with Stynylerez.

 

7. With Stynylrez you will be able to proceed with the final coat of top paint.

 

If this does not work t is not the fault of the above. It must be the plastic which

I cannot imagine it being at fault.

 

Do not give up. Providing this is followed to the letter I am sure you will not have problems.

Let us know that you are successful. Not if. But you are.

 

Laurie

 

 

[walkerccw]

Thanks Laurie.

 

I just ordered the Stynylrez from Amazon.  Will be here Friday.  I will follow your directions to the letter and let you know.

 

Curt

[Fernando]

Hi, all,

 

I use primarily Xtracrylixs and peeling off occurs from time to time. I usually prime the models with Alclad Grey primer (or a gritty grey enamel like Humbrol's). It happens more often to pieces not primed (like single-piece external stores). Xtracrilixs allows the spot be sanded smooth (provided the paint is thouroughy set, otherwise it starts peeling off) and retouched. It is very forgiving in such sense.

 

Fernando

[Murph]

I refuse to use Model Master Acrylics.  They go on thick, sand terribly, and come off in chunks if you simply walk by the model holding some masking tape in hand.  I've even had the Model Master paint I sprayed over a masked off area come up in sheets when I lifted the masking tape, while the Gunze-Sangyo paint underneath the masking tape was fine.  Tamiya and Gunze-Sangyo are much more resistant to peeling, and I've found Xtracrylics to be better also but not as durable as Tamiya or Gunze.

 

Regards,

Murph

Edited October 13, 2016 by Murph

[walkerccw]

HI Laurie,

The Stynylrez came in and I have started the process you described.  Getting the old paint off was easy using 3M Painters tape!

I have 2 questions for you:

 

1. How long should the Stynylrez dry before putting on my first coat of acrylic? It seems to dry very fast, and it goes on so much smoother that the Model Master Acrylic primer.

2. How long would you wait between coats of the acrylic paint?

 

Thanks a lot.

 

Curt

[LaurieS]

Hi Curt.

 

Under normal circumstances I have filled, sanded and airbrushed the finishing coat each about 2 hours after the "Styno" has been applied.

 

However as you have been having problems I would if you can be patient leave for 24 hours. Patience versus enthusiasm which is it to be.

 

What you could do if you have a small piece of the plastic is to "Styno" leave for 2 hours and have a go with the top coat.

 

Best of luck.

 

Laurie

[LaurieS]

Overlooked the second question Curt.

 

Only know about Vallejo Lifecolor MIG and AK. With these I give 24 hours. But if I am going to mask, apply decals ect up I leave 48 hours.

 

In applying the top coat with the above paints I give a thin starter leave a few minutes then coat up and as the surface drys from being wet another coat.

if it is a largest item, 1/48 helicopter for instance, by the time I have coated all around the starting point is near dry to apply another coat.

 

Laurie

[walkerccw]

Laurie,

 

I just completed the first part of the process on a small part.  I waited 4 hours after applying the Stynylrez, masked and put my first coat of Model Master acrylic.  When I pulled off the tape the Stynylrez  did NOT lift off!!!

 

Tomorrow, I will mask over the Model Master acrylic, paint the other half, and see if the Model Master Acrylic will lift off.  I will wait 24 hours before I take the tape off.

I will keep you up to date.

 

Curt

[walkerccw]

My first tests with your method worked great!

 

Washed

Sanded

Stynlrez

Mask

Model Master Acrylic first coat

Model Master Acrylic second coat

Unmask (no lifting!!!!)

Repeated process.

 

I will try on a bigger piece of the kit and let you know.  I am off to watch American Football, Baltimore Ravens vs New York Giants).

 

Curt