Poor Paint Adhesion

[Disillusionist]

Lately I’ve been sharpening my Aztec painting skills on everyone’s favorite 1/350 starship. I’ve decided to use automotive lacquers just as was done on the original studio model. It’s been working out reasonably well except for one annoying problem. Paint lifting. I’ve tried a number of things to eliminate the problem, but it keeps rearing its ugly head. I’ll give a rundown on the materials and techniques I’ve used and hopefully someone might have had a similar experience or an idea or two as to its cause.

The primer I’ve used is Duplicolor White Sandable in spray bomb format. Once it was sprayed and dry, I sanded it with 600 grit paper. Over the primer I’ve sprayed my pearls. These are House of Kolor powders (red, green, blue, and gold) mixed with PPG DCA-468 High Performance Clear Acrylic Lacquer. An overall thin layer of blue is applied to each area, followed by the main Aztec in green, then the other two colors in secondary patterns, topped off with more random shapes in blue.

The lifting problem seems to occur anywhere in the process when I’m removing masking material and lifts all the layers leaving the primer intact. You can look at the underside of the tape and see that there doesn’t appear to be any primer coming off…just the pearl clear coats. The problem still occurs even if the paint is given days (sometimes weeks) to dry before applying overlapping areas, and it always takes off ALL of the pearl layers right down to the primer.

I’ve tried different paint/thinner ratios to no avail. I thought that perhaps the DTL876 medium dry time thinner I was using was flashing off too quickly, not allowing the topcoats to melt enough into the primer. So I switched to the “slow” DTL105 thinner. This did seem to help a bit, but the problem has reared its ugly head once again. I’m wondering now if there is an incompatibility between the Duplicolor primer and the PPG paint. This seems unlikely to me being that everything I’ve heard about the Duplicolor says that it’s lacquer friendly, although I can find nothing on the can or on their website that says whether or not it's an enamel or a lacquer paint.

So far, I’ve managed to repair the areas this has occurred in by sanding and re-priming….But, Geez!!! What a pain in the butt! These are high quality products I’m using, (albeit in an unusual manner that the manufacturers probably never dreamed of), and I would really like to see this all work out.

Oh well, enough babbling. Here’s a picture of the problem in all of its iridescent ugliness. Any ideas?


http://i166.photobucket.com/albums/u96/ ... dpaint.jpg

[Lt. Z0mBe]

The missing component here is the pressure you are shooting the pearlescent paints at. They're mixed with a lacquer that's chemically "hot" but, as such, it also evaporates like no one's business.

Let us know your pressure and maybe we can help. Pearlescents and metallics are finicky anyway, but the more collective hammers we can give you to pound on them, the better.

Kenny

[Disillusionist]

Generally between 20-25 psi. They do seem to go on wet and shiny,

especially since I switched to the slower thinner.

[Lt. Z0mBe]

I generally shoot metallic lacquers at 12 to 15 psi. Make sure it's 12-to-15 when the trigger is depressed - look at the pressure gauge on your regulator after pressing the trigger.

One other thing I thought of. With metallizing lacquers - at least the hobby grade ones - you often have to top coat them. I top coat Model Master metallizer - after it's dried - with a 50-50 mix of Future and 90-percent isopropyl alcohol shot at 12-15 psi too. I mask with low-tack stuff when I need to mask (sticky notes, Tamiya tape, liquid latex), and generally have no problems.

Here's the caveat - I mask, using the method above, after everything had a buttload of time to cure. The lacquer cures relatively quickly ( a few hours) and I give the Future 24 hours. I also very lightly seal the edges of the mask after burnishing it down. I seal the edges of the mask with a super light mist of the color being masked off to prevent bleed under.

I don't know about the lacquers you use, so I would test the topcoating method.

I hope this helps.

Kenny

[Disillusionist]

I'll give reducing the pressure a shot. Although, I'm not sure about top-coating. The clear that I'm mixing the pearls with really is a topcoat in itself. But, then again, maybe mixing the powders with it changes its properties. Hmmmm...I wonder if too much powder added reduces the integrity of the paint film. Something else to consider.

Thanks for the help!

Matt

[Migmaker]

same thing happened to me too...found out the primer i used wasn't compatable with the true laquer paints...make sure they are before wasting hours of painting work.
Will

[DX-SFX]

If it's going on wet, it's not an air pressure issue. As Migmaker suggests, it's more likely a compatibility problem. You could ask the manufacturer of the pearlescents what primer they recommend.

[Mark Yungblut]

I am in agreement with the idea that the undercoat could be part of the problem. Additionally, I would enquire as to how long to let the paint cure with either the retailer you purchased it from or the manufacturer. Typically paints like that can take up to 48-72 hour to fully cure. Also, think about switching to a masking material that is not as adhesive. I really like using Scotch brand removable tape. The secret is to mask the subject then spray it with a layer of the color you just masked. This adds to the overall finish time because it has to cure, but it also has the benefit of sealing the mask job prior to painting the next color.

Another factor can be temperature and humidity these two can greatly affect paint curing and in some instances prevent the paint from fully curing. This is why most Auto paint shops bake the paint between layers of color.

I have successfully made a large "Curing Booth" with a large cardboard box and a 40 w incandescent bulb. As long as the bulb is not right near the plastic model, it will provide enough warmth to cure the paint. This also has the added benefit of giving you a cleanable relatively dust free area for the paint to dry then cure.

Hope this helps,

Mark

[Antenociti]

when using Alclad 2 pearlescent lacquers ihave found that they bind a lot better to the Alclad primer than to standard automotive primers, so now i always use the acladl 2 primer in areas that will be covered by the pearlescent alclad 2s

[Newbie Doobie]

First of all,Duplicolour doesn't make lacquer no matter what they claim! They only make acrylic products! Lacquer is made from nitrocellulose. Sherwin Williams is the maker of Dupilcolor. Plastikote makes TRUE lacquer! Contrary to their name,they specialize in all kinds of paint coatings,and ARE the original patent holders,and makers of automotive,and furniture lacquer - NOT Duplicolor! Paint manufacturers pay top dollar for licenses to produce high solvent based finishes. These are automotive finishes,and are used with hardeners,and reducers. Reducer helps the paint to flow out smoothly out of a spray paint can,and hardeners make the finish cure faster than flash dry,or force drying with a heat gun. The binder,or base will determine what type of adhesive properties,and curing time,as well as durability a finish has. PPG paint is now largely polyurethane based,and will be incompatible with most solvent based paints. This was originally made for the automotive industry to combat the checking(cracking)that usually occurs with traditional lacquer. What you need is intercoat clear that keeps tape from removing the paint under it. This seals the paint coats,and keeps tape lines out of the finish to ensure a smooth finish surface. Most paint isn't fully cured for at least a year. Plus extremely thin paint has no durability to tape pulling,as there isn't a thick enough film to be resiliant to damage. This only invites scratching,and premature wear,and tear. Spraying multiple coats of intercoat clear over the base helps give it durability,and intercoat clear dries faster,and harder that store bought clearcoat out of a spraycan. This can be sprayed over multiple coats without fear of yellowing,or looking too thick! This is House of Kolor polyurethane,and will be compatible with acrylic without crazing,and wrinkling.

[Kylwell]

Dude, mellow out. Lacquer can, and is, be acrylic based. Remember, acrylic is just the color.

[Newbie Doobie]

Actually acrylic is the base,or binder that the substrate is made from. Lacquer is never made from an acrylic substrate! The reason that they call it lacquer is because it's a in a high solvent base. Meaning that the chemical composition is had methyl ethyl ketone,and zylene in it,not nitrocellulose! Just because it has a high solvent based chemical concentration deosn't mean that it's lacquer! Paint formulation is like any other recipe. It has to follow the original recipe to be that exact element! Dupont introduced the acrylic we know today in 1955,as enamel lacquers which anyone who knows paint formulation understands that there is no such thing as enamel based lacquer as the two are incompatible! They only called it lacquer because it was intended for automotive use!

[Disillusionist]

I guess that's why some of it is called Acrylic Lacquer, eh?

Either way, I switched from the Duplicolor primer I was using to Plasti-Cote and haven't had a problem since.

[Kylwell]

All right. Then Plastikote doesn't make 'true' lacquer either.

After all, they don't use Toxicodendron vernicifluum in their mix.

Acrylic lacquers

Lacquers using acrylic resin, a synthetic polymer, were developed in the 1950s. Acrylic resin is colourless, transparent thermoplastic, obtained by the polymerization of derivatives of acrylic acid. Acrylic is also used in enamels, which have the advantage of not needing to be buffed to obtain a shine. Enamels, however, are slow drying. The advantage of acrylic lacquers, which was recognized by General Motors, is an exceptionally fast drying time. The use of lacquers in automobile finishes was discontinued when tougher, more durable, weather- and chemical-resistant two-component polyurethane coatings were developed. The system usually consists of a primer, colour coat and clear topcoat, commonly known as clear coat finishes. It is extensively used for wooden finishing.

[Newbie Doobie]

You'd be correct! I too switched to plastikote(the can with the picture of the fender painted half red on it) from duplicolor! I've used plastikote for twenty years now,and I've never had a problem with their lacquer products. In fact,I have a Monogram '57 Chevy in 1/12" scale that I painted back in 2000 with Plastikote black laquer. I'm in the process of finishing this now. I haven't worked on it forever,but now I'm going put the final pieces together. I'll post a link to pictures of it tomorrow.

[Newbie Doobie]

All right. Then Plastikote doesn't make 'true' lacquer either.

After all, they don't use Toxicodendron vernicifluum in their mix.

Acrylic lacquers

Lacquers using acrylic resin, a synthetic polymer, were developed in the 1950s. Acrylic resin is colourless, transparent thermoplastic, obtained by the polymerization of derivatives of acrylic acid. Acrylic is also used in enamels, which have the advantage of not needing to be buffed to obtain a shine. Enamels, however, are slow drying. The advantage of acrylic lacquers, which was recognized by General Motors, is an exceptionally fast drying time. The use of lacquers in automobile finishes was discontinued when tougher, more durable, weather- and chemical-resistant two-component polyurethane coatings were developed. The system usually consists of a primer, colour coat and clear topcoat, commonly known as clear coat finishes. It is extensively used for wooden finishing.

This wasn't part of their formulation! Everyone's a critic! You have to be very careful what you read on this wikipedia website as you don't know how accurate the information is! Or who's posting it!

[Disillusionist]

Actually, looking at the Duplicolor can and website...nowhere (that I can find) does it state that their sandable primer is a lacquer or enamel...or watercolor for that matter.

[Kylwell]

All right. Then Plastikote doesn't make 'true' lacquer either.

After all, they don't use Toxicodendron vernicifluum in their mix.

Acrylic lacquers

Lacquers using acrylic resin, a synthetic polymer, were developed in the 1950s. Acrylic resin is colourless, transparent thermoplastic, obtained by the polymerization of derivatives of acrylic acid. Acrylic is also used in enamels, which have the advantage of not needing to be buffed to obtain a shine. Enamels, however, are slow drying. The advantage of acrylic lacquers, which was recognized by General Motors, is an exceptionally fast drying time. The use of lacquers in automobile finishes was discontinued when tougher, more durable, weather- and chemical-resistant two-component polyurethane coatings were developed. The system usually consists of a primer, colour coat and clear topcoat, commonly known as clear coat finishes. It is extensively used for wooden finishing.

This wasn't part of their formulation! Everyone's a critic! You have to be very careful what you read on this wikipedia website as you don't know how accurate the information is! Or who's posting it!

i give up.

Lacquer, originally, was Chinese in origin, using sap from the Toxicodendron vernicifluum tree.

[Newbie Doobie]

Actually, looking at the Duplicolor can and website...nowhere (that I can find) does it state that their sandable primer is a lacquer or enamel...or watercolor for that matter.

The can I had said sandable lacquer primer. But,like I said before,I use plastikote primer now,and it has been a long while since I bought Dupicolor,so it might not say that on the can now.

[Newbie Doobie]

All right. Then Plastikote doesn't make 'true' lacquer either.

After all, they don't use Toxicodendron vernicifluum in their mix.

This wasn't part of their formulation! Everyone's a critic! You have to be very careful what you read on this wikipedia website as you don't know how accurate the information is! Or who's posting it!

i give up.

Lacquer, originally, was Chinese in origin, using sap from the Toxicodendron vernicifluum tree.

Actually,lacquer was originally from Japan,and the idea was imported to China! EYEGLASSES WERE ORIGINALLY FROM CHINA. This wasn't the same formualtion that plastikote used. Theirs is actual automotive finish,and not the hand-rubbed french polish type that originated 600 years ago. The Japanese formulation was actually a quartz enamel rubbed on by hand,and polished with wood bore alcohol. This is what many guitar makers in old world Spain used to finish their classical guitars with! This was used until shellac was introduced 100 years later. This was polished by using the French polishing technique. A cotton "tampon",or "buff" was applied to it then rubbed viogrously by hand. This was then buffed afterwards with linseed oil thinned with alcohol. The lacquer we know of today was made from tree gum spirits(nitrocellulose),and NOT acrylic! Many people think that lacquer is a generic term when,in fact it's not! There are many paint makers who put lacquer on their product labels thinking the general public wouldn't know the difference! What's really sad is - they're right! Many people DON'T KNOW THE DIFFERENCE between the two! I'm not trying to piss anyone off here,but rather give them a truly informed view of these products from a veteran unionized painter! I've been a painter forever,and I have HAZMAT,and HVLP,asbestos removal,and CPR certfication,and industrial,and automotive painting experience. I'm not trying to entertain you,but rather inform you so that you WILL know the difference! And,not paint your project with something that will damage it thinking the two products are the same,only to ruin it with two entirely incompatible paint products,and left wondering why! I had this problem when I painted a model when I was a kid,then I repainted it later only to have it destroyed by two entirely different finishing products! Lacquer eats enamel,and acrylic products,and the two are never to be used together! You can paint anything with lacquer first,then paint a different finish over it,but NEVER the other way around! Any paint jobber will tell you the exact same thing! You can paint your model with lacquer,then let it dry,and spray acrylic clear,or enamel OVER it,but NOT UNDER IT! I hope that this will clear up any misunderstanding that any of my previous comments may have caused! It wasn't my original intent to confuse anyone reading this!

[Kylwell]

Well dude, all I can say is that according to every dictionary I can find and US patent & copyright office, lacquer is a generic term.

[Newbie Doobie]

Well,you can look it up in the national library of congress like I did,and the U.S. patent office,and see that it's NOT a generic term! And if you're looking in websters' dictionary-an expert is"a drip under pressure",and a fart is"a small explosion between the legs"! So, I don't give much creedence to what definitions they have for everyday items,as the people who print this rubbish-don't specialize in automotive paint technology!

[Kylwell]

USPTO, take your pick. Library of Congress? Come on dude, at least pull out something relevant. How about MSDS sheets? Lacquer primer, Sherman-Willaims; Bulk acrylic lacquer, Dupont lacquer... oh look, they're all different. How could that be if it's a copyrighted/owned term?

[Newbie Doobie]

How is the library of congress irrelevant? This is where all these types of historical discoveries are stored. When,where,and by whom. I didn't say it was copyrighted,it was patented by them. The word lacquer may be generalized,but not the formula!

[Kylwell]

Then give us a link, because all my searches there come up with proper care of LP masters.