Cleaning plastic before priming, and...

Hi Rich,

For cleaning prior to priming/painting, all you really need is a gentle wash in warm water with a little dishwashing liquid. Some people will spray down a model with Windex or wipe it down with isopropyl or denatirured alcohol, or use one of those purpose-made "plastic prep" solutions - often it comes down to personal preference.

Is priming really necessary? Again, that's often a matter of personal preference. As I mentioned in a previous post, I've been primarily using Tamiya acrylics and don't really feel the need to prime first, but that's just me.

However, not all acrylics are created equal. for example, ModelMaster acrylics seem to be notorious for adhesion issues and require both a spotless surface and a primer coat for best results. Vallejo paints seem to use a milder solvent (I believe it's an alkali based solven, ie. not alcohol basedt) and has lower adhesion on bare styrene..

When to prime/paint? Generally, it's better to assemble as much as you can before painting. Look at the assembly sequence and identify sub-assemblies made up of multiple parts which are to be painted a uniform colour. The only real exception is where access to a part after assembly will restrict your ability to paint it. Some people do prime parts before assembly, but as you noted, cleaning up attachment points and filling seams will require re-priming (and thus more paint). Priming before assembly may also result in paint being deposited on mating surfaces to be glued, Thsi will weaken the bond, as paint and glue don't mix (well, they do mix, but you end up with something somewhat more than paint, but less than glue).

In addition to giving your top colours a good base to adhere to, priming also helps show up any flaws/gaps/lumps in seams and joints which may require attention. I would only sand the primer if it revealed any flaws requiring attention, otherwise just paint straight over the top.

Rich,

I'd like to weigh in on this one if I may...

First cleaning of the kit.  I personally have never cleaned a kit before doing any priming, painting or anything else for that matter.  It may just be my luck; but I've never had any issues with paint adhesion.  My painting is pretty evenly split between Tamiya acryllics and Testor's Model Master enamels. 

I do prime all my parts though, religously.  I don't go for the fancy (more expensive) Tamiya primers though.  I simply use cheap ole 94 cent a can DupliColor spray primer.  I mainly use it to point out imperfections in my work before painting. (i.e. seams, small sinkholes, etc.)

Again, this part is merely my own personal taste, I build the model into it's major sub-assemblies (i.e. turret, upper hull, lower hull, road wheels) then prime those bigger pieces doing any sanding and filling as necessary.  If I do any filling I cover that area with a little primer just to keep the overall color uniform.

You're bound to get a whole lot of opinions on how to do this.  You'll probably want to cherry pick the best ideas and incorporate them into your own style.

Best of Luck!

Richard S.

Ditch wrote:

Hi again,    Wow, have I been getting some great info on everything by just reading all the forums! One thing I haven't come across yet is what everyone recommends for cleaning the plastic parts before priming as many have suggested? And if most of you feel it's really needed anyway when using acrylics? Also, when you prime all the parts, do most of you prime them before removing them from the ("cards"?) they come attached to? Then just touch up the attachment points after removing and de-burring, etc.? Or is that too much handling of the primed surface? Oh ya...(sorry), and large parts, do you sand the primer at all before shooting the color? Wow...get all that? Thanks, Rich

Phil & Richard,

   Thanks to both of you for the information. Like I had mentioned, I'm going to pick up a cheap kit of (whatever???), just to try out various ideas. Also, I've changed my mind after having done more research, and having read quite a bit from these forums. So for numerous reasons, I've decided to go ahead and get the gender reasignment proceedure after all..... ....uh????........sorry, wrong forum! I mean I've decided to go with the Tamiya acrylics rather than Vallejo. I'm hoping it's the way to go for me? So thanks again guys.

Rich

Not so sure on the gender reassignment, but if there's one thing I do know is painting. Ok, that's a lie. But I'm pretty good at it.

Like Richard, I use a lot of Model Master Enamels and Tamiya Acrylics. The difference is I build aircraft. Also, I only clean model kids that feel "greasy". ICM is notorious for this. Just a quick dunk in some dish soapy water ought to do it! Make sure you rinse well! Ok, here's my steps for painting:

1)I usually start with the interior color(s). I cut all the interior pieces and paint them the proper color. If I use enamels, I usually don't prime, but if I use acrylics I do. My primer consists of a light gray Model Master Enamel cut with lacquer thinner.

2) I assemble the model as much as I can. I prime and paint wheel wells the proper color and mask them off.

3) I prime the exterior.

4) I paint the exterior the proper colors, going from lightest to darkest.

5)Clear coat, decals, clear coat, washes, dull coat, final weathering

 Hope this helps!

Rad...(or do I call you Mr. Max?),

   I'm not sure on the gender reassignment myself? You see, I'm really not very attractive as a man or a woman. (Although my calves look spectacular in a nice pair of pumps!)

   Moving on...Thank you for your advice, the more the better for me. When you say you thin your primer, is that just regular thinning for proper airbrush consistency, or because it gives a better end result?

   Also, when you clear coat prior to washes/weathering, what do you like to use? (For acrylics.) And you wrote that you use two clear coats...then a dull coat. So I'm assuming when you say "clear coat" as opposed to "dull coat", that means the clear coat is a gloss...or semi-gloss? Why do you do this? And what if I don't want the end result glossy/semi-glossy?

Thanks in advance...uh?...Mr. Rad Max

Rich

Rich, my name is Max, but my friends call me Max.

Anyways, I see you have a couple more questions. I'll try to answer them clearly.

When I say thin my primer, I mean thin it for airbrushing. The reason I use lacquer thinner is because it gives the paint a little more "bite" on the plastic, meaning the paint will probably not chip off.

I use a couple products for clear coating. The old standby is Future Floor Polish. It's an acrylic floor wax that can be sprayed in your airbrush. I've also been using a Lacquer clear coat from a rattle can. And yes, when I say clear coat I mean a gloss coat, the glossier the better.

The reason I do this before applying decals is to create a smooth surface for the decals to adhere to. Otherwise you get decal "silvering", which is when airbubbles get trapped beneath the clear parts of a decal and mess up the looks.

The reason I clearcoat after decaling is to seal the decals. This also leaves a nice smooth surface to add washes to. It makes it easy to wipe up the excess wash. 

If you don't want the glossy finish on your model, just coat the entire thing with a dull coat. This will take any shine away. For this I've used a few different techniques: A rattlecan flat coat, Future with Tamiya XF 21 mixed in (It's Tamiya's flat base... use a 4:1 ratio to obtain a FLAT finish, 10:1 for a satin etc), and a product from Microscale.

Hopefully this helps! Good luck!

   Ok...so just to be straight, you only usually prime when using acrylics. Yet when you prime for acrylic paints...you use a lacquer based primer, not an acrylic or water based primer. Have I got that right?

Rich

OK I can see where you'd be confused.

When I paint cockpits with acrylic paint, I use an enamel paint (any will do) thinned with lacquer thinner. WhenI paint the exterior, I prime with the same stuff no matter what. My reason behind this is that sometimes acrylics don't have the best adhesion qualities. Also, the exterior will be handled and priming reveals seam flaws.

Here's my routine when painting with acrylics:

• Wash all of the kit pieces in warm water and dishwashing soap before assembly
• Assembly as much as the kit as possible
• Soak the subassemblies in warm water and dishwashing soap for 10 minutes
• Allow to dry
• Wipe down areas with Polly Scale Plastic Prep and allow to dry
• Airbrush acrylic based primer
• Fix any flaws, wipe down with Plastic Prep again, reprime
• Airbrush final colors

For acrylics, I primarily use Model Master Acryl paints.  The above routine is what is recommend by Testors.  So far, having followed the routine, I haven't had any problems with adhesion.

-Jesse

Thanks Max,

   Now I get it, and thank you for the clarification!

Rich

I've found that newer kits from Hasegawa, Tamiya, Eduard, etc. are not nearly as bad as older kits I've built from Academy (I use a 1/72 B-17 wing from this kit as an example of what happens when you try and paint unprepped plastics - ugly!), Revell and others.

Regardless, I now follow most of what Jesse does - I wash all of the major parts with a soft toothbrush in warm soapy water and let dry.  If I've been over-handling the plastic and don't want to wash it again or its in major assemblies, I use one of the plastic prep solutions topically.  

I almost exclusively paint with acrylics as well, esp Model Master, Polly Scale and Tamiya.

The other benefit of the pre-wash is you get a good look at the pieces before you start to build.  Once in a blue moon you find parts missing, damaged, or warped.  Better to see this ahead of time!

usmc1371 wrote:

Here's my routine when painting with acrylics: Wash all of the kit pieces in warm water and dishwashing soap before assembly Assembly as much as the kit as possible Soak the subassemblies in warm water and dishwashing soap for 10 minutes Allow to dry Wipe down areas with Polly Scale Plastic Prep and allow to dry Airbrush acrylic based primer Fix any flaws, wipe down with Plastic Prep again, reprime Airbrush final colors For acrylics, I primarily use Model Master Acryl paints.  The above routine is what is recommend by Testors.  So far, having followed the routine, I haven't had any problems with adhesion. -Jesse

Okay, I have a question...what do you think of sealing the paint between coats??  (i.e. Testors' Dullcoat between camo colors)  I'm painting a F-104 in Southeast Asia camo scheme. 

I have only had 2 times that I have experience adhesion problems with Model Master Acryl paints: the first time there was no primer coat (I think I did not allow adequate dry/cure time between coats and masking ), the second time I had a primer coat, waited almost 2 months and the masking still peeled in two small spots (not sure at all what happened there). 

This time, I cleaned the plastic before assembly, then before painting wiped it down with isopropyl alcohol.  I didn't prime it and just finished shooting the light gray underside color.  This is a gift build, so I don't want to run into huge problems.  Any thoughts?   

Max,

Just a minor point, but Future is not a wax or a polish.  It is a pure acrylic finish that acts as a strong clearcoat to protect the paint.  It's a great product for its intended use too - great way to make older, cleaned as best as possible, floors look shiny and newer.

In years past it was necessary to wash, as manufacturers used an oily mold release agent.  Today I only wash old kits bought at flea markets and such, or from very small mfgrs, a few of which apparently still use the release agent.  Also, many resin kits are from garage shops and it is always a good idea to wash them.

loulovesspeed

Max,

Just a minor point, but Future is not a wax or a polish.  It is a pure acrylic finish that acts as a strong clearcoat to protect the paint.  It's a great product for its intended use too - great way to make older, cleaned as best as possible, floors look shiny and newer.

 

 

Another zombie thread revived. LOL!

You do realize this is a 10 year old thread right? By now, I’m sure Max has it all figured out by now.

Don Stauffer

In years past it was necessary to wash, as manufacturers used an oily mold release agent.  Today I only wash old kits bought at flea markets and such, or from very small mfgrs, a few of which apparently still use the release agent.  Also, many resin kits are from garage shops and it is always a good idea to wash them.

 

 

I think washing spues to rid of any residual oils today is still a necessity even today.