Primer Test - Part I

ready

These are exactly the same three I was going to test side by side.

I will be following your test closely,,,,,and will do whatever parts you leave out or bypass.

My own personal list of what a primer has to do are these things:

It has to stick to plastic and putty all on its own. For that I burnish down some tape, then remove the tape to test the primer's adhesion.

It has to sand, otherwise, as you say, you can't primer, make repairs, primer, etc. (this would really disrupt the whole fill, sand, primer, sand, fill or primer, sand, etc, etc routine)

then, no matter how well it sticks to plastic, how well it covers over colors, or how well it sands,,,,,,,,,paint has to stick to it with the same masking and removal test.

In both of our cases, we need something besides smelly, toxic lacquers and enamels,,,,,,if Polly Scale and Aeromaster and LifeColor won't adhere to my primer,,,,,,I might as well be using Enamels,,,,which is not an option anymore here at the Hangar Deck.

Rex

ps, I bought the Stynylrez based on your posts here on FSM, took the opportunity to pick up some Badger parts while I was at it,,,,,,,,,,so far, I love the quick drying time of the Stynylrez.

The Vallejo primer is not sandable.  It is less durable than AK and Tamiya.  The Vallejo primer doesn't bite the plastic.  Instead, it forms a rubbery surface on it.

You'd better clean your AB with lacquer thinner or denatured alcohol after shooting the Vallejo primer.

I have never had an issue with cleaning the Vallejo with the Testor's airbrush cleaner.  I have used Vallejo on several models.  I also hear good things about the Vallejo airbrush cleaner but I haven't tried it.

Just an update after 16 hours only the AK seems to have any odor left to it.  I think I will do a 24/48/72 hour test and see if there is any difference.  Rex;  thanks for taking up my slack.  With this being a test on just a smooth surface, it might be good to try it on a rough surface or two sections of card glued together where there would be a seam.  my hunch is that once there is a "crack" in the primer, it may get pulled up from that point going forward.

John

I've used and have Vallejo, AK & Tamiya primers.  In my experience, the AK & Tamiya are more durable and adhere to the plastic much better than the Vallejo primer, based on my trusty "scratch the surface with a toothpick" method.

BTW, the Testor & AK cleaner both have denatured alcohol as an ingredient according to the folks at other forums.  

looking forward to what happens

Rick

Not at all a scientific method of evaluating, but I've noticed that acrylic paint seems to me to dry to a hard and durable surface, even somewhat scratch resistant when compared to enamel. More than once while handling Model Master flat enamel painted models, I've left finger nail marks behind. Clear coats of course take care of that. Since MM enamel apparently is softer than acrylics, several times I have used it as a primer. A few light coats a couple of minutes apart, let cure overnight, then a light sanding with WELL USED 600 grit and it sticks well, doesn't strip away. Seems to me to do a very good job of filling and finding the little flaws that I was looking for, I think it leaves a well prepped surface for the final finish to lay down on. I've even experimented with adding a bit of lacquer thinner to the MM flat paint, which seems to me should give it even more bite for adhesion to the plastic. I didn't notice any reaction between that and the acrylic sprayed over as final finish, but I was just testing a bit to see if it would react. Indeed there was no need for it, as like I said, I've never had the MM scrape away with sanding. For what it's worth, I have found the acrylic primers to be a good bit more touchy and sometimes unpredictable, the old time MM flat enamels just seem to be (for me) a predictably user friendly and forgiving medium, for priming and sanding. There, those are my two pennies. Patrick

OK, the results are in on the 48 hour test.  I wanted to do a 24 hour one, but the AK still had a faint odor.  Neither the Vallejo or the Badger had any after 24. After 48, all was quiet on the sniffing front:)  Now to what I found.

I first put down a section of the Staples version of Blu-Tac.  It is grey but I am sure works the same way as I have used it just like Blu-Tac.  I also then put down a section of Tamiya tape, and then one of Scotch Blue Painter's Tape.  I have no need to try a heavier tack tape.  I did NOT de-tack any of the tapes, just from the roll to the card.  I let them sit 30 minutes and then peeled them off.

All passed with flying colors.  There are two little scratches on the Badger (black) section and those were due to me picking at the corner of the tape.  More to come there.

Next was the sanding.  I used some 180 grit and some 320 grit paper straight from Home Depot.  not sure how this may equate to various hobby grits.  Below is the result of sanding both grits.  things degrade a bit here, so let me sum it up.  Again, this is MY unscientific test.

1.  Both the Badger and the AK sanded off very easily and when I ran my fingers along the sanding area, it was very smooth.  I could not detect and edge.  the Vallejo came off in smaller "chunks" and the edge was palpable to my fingers.  I could feel the edge.  The Badger and AK came off as a fine sandy dust.

2.  All did much better with the smoother 320 grit.  I am going to say that the finer the grit and the "softer" the sanding action the better.  However the end result was the same as number 1 above.

3.  I was able to use my fingernail and scrape off all three.  Consistent however with the above results, the AK and Badger was smooth to the touch and the Vallejo was detectable to my fingers. 

So what are MY conclusions:

1.  None of them will give you a primer coat that cannot be scrapped off.

2.  All will adhere to the plastic without lifting after drying.

3.  the Badger and AK are so close as to be a tie for the "best" for sanding and keeping a smooth surface.

4.  All are easy to clean with no unpleasant odors and gave my airbrush no problems with water and airbrush cleaner for cleanup.

5.  All come in a variety of colors.

In the end, I will be using the Badger and the AK as my first choices and continue to see how they perform.  If I know I have a large area where I know I won't need to sand, I my use whatever I find is within reach.

I am going to forgo the 72 hour test and do a spraying over them and see how the paint adheres to the primer.  that will come over the next couple of days.  Thanks for reading and anything you all have would be appreciated I am sure by all of us who are trying to find that perfect primer.

I told you that Vallejo was not sandable.  The Vallejo primer is the worst I've ever used, and there are several horror stories of using it at other forums.  When I bough 6 bottles of the Vallejo primer last year, I wasn't aware of its weaknesses.  I mostly use Tamiya and AK primers nowadays and couldn't be happier.

I am not disputing your findings.  The purpose of this was to try to show those who might be on the fence what I found.  There was a gentleman on another thread awhile back who claims that you can sand Vallejo, so I thought I would try them all out side-by-side.  I just thought it might be of interest to present my unscientific test and let folks see and draw their own conclusions.

John

Nice job

John, your post will help many people!  

If someone had posted this kind of experiment last year, I wouldn't have bought Vallejo primers.  I wasted a lot of time (and my sanity) figuring out why I couldn't sand Vallejo primers.

same here, Chrisk-k, I bought the 200 mil gray, the 200 ml white and the 60 olive drab when that thread ran on here.

The good news is that I can use the white as my first white paint coat over primer, and use the Olive drab to do bomb body color. Over AK or Badger primer, of course.

I bought 6 bottles of Acrylic primer since the discussions started on FSM,,,,,,,and can actually use the last three, lol. And because I started to get leery toward the end, those three are all the smallest bottles.

I will be getting the larger bottles of Badger's primer next time I get supplies, though.

Rex

I too bought a 200ml grey and 60ml black and 60ml dark grey.  I was thinking the same thing as using the grey (almost white) over the Badger since the light under side RLM colors do better with a light primer.  I looked last night and Stynylrez was out of stock on Amazon.  Where do you all purchase it?

On a follow up, I sprayed some RLM light blue over the primers and will let them dry until tonight and see what happens on the tape test.  

John

I'm stuck with five 60 ml Vallejo primers in various colors. One nice thing about Vallejo primers is, once cured, they are impervious to alcohol. If I want winter camo or heavy chipping, I spray a Vallejo primer as a base coat, let it cure, and spray Tamiya over it. Then, I soak a brush in IPA and scrap away. Super easy. No hairspray is needed.

you can get Stynlrez at Webairbrushes.com

I used the postage to get a few airbrush spare parts while I was at it,,,,,and I tried a Badger Military paint color (not a close enough match for anything)

the primer is halfway (or more) down the paints page

Rex

Rex; thanks.  Chrisk; good tip.  I now have a reason to try that technique:)

John

I was certain they didn't have any last time I looked at webairbrushes.  Thx.

So I masked all three again with the three different masking options as below:

I am happy to report after 30 minutes when I lifted them off, there was no lifting:

So if you don't need to sand, they all work great.  If you want to sand, stick with Badger or AK.  There shouldn't be any worry about masking any of them.  Now I am sure someone will not have the same results I did, but I didn't do anything out of the ordinary.  I prepped the plastic, sprayed, cured 48 hours for the primer and 24 for the acrylic paint.  I am off to try the Badger and AK on a real model kit next.

John

Should have said that I sprayed Vallejo acrylic Model Air light blue over the primers.

John

Thanks John,,,,,,,,,,that about covers everything I need to know. If you can get Model Air to stick to the Badger and AK primers, then we don't need to worry about sanding anymore.

I will just use up my Vallejo primer in non-sanding roles,,,,,,,or in places where they can be a color coat, just like paint.

Most of my painting for about the next decade or so is going to be Aeromaster or Polly Scale over AK or Badger primers,,,,,,,,the little bit of LifeColor and Vallejo/Italeri I will use, I will just treat with kid gloves until I can get some AquaGloss or Aeromaster Clear sprayed over them. Hand brush Acrylic painters know that Polly and Aero can be brush painted onto parts that won't be masked without a primer at all.

Rex

ps, one small thing for me to check on is to see if the Vallejo primers paint and adhere okay over the AK and Badger primers

Rex;

I was wondering that too as I don't want to use a black primer under a light RLM color although it did fine in my test.  I was thinking of the Vallejo grey/white on top of the black.  I will give that test a run through this weekend.

I am working on Airfix's 1/72 Fw-190 A/8, and I sprayed RLM02 in the wheel wells and RLM66 on the cockpit interior section over the bare plastic.  All I did was wash the plastic, and the Vallejo Model Air did not lift when I tried to using the Scotch Blue tape.  I think the key is to wait 24 hours for the paint to cure (even though it seem dry on just a few hours) and make sure the plastic is prepped properly.

John

I decided to push things a little and see what I could get.  I sprayed the Badger black over a large section on the card.  After 6 hours, I detected no odor and decided to spray the Vallejo over it in three different patterns.  Fine mist to lighten it, almost total coverage in multiple passes, and blast a full on heavy coat on.  I separated each section with a piece of Tamiya tape.  I then waited 6 more hours and did my tape test just with Tamiya.  See below the result with the misting on the left and the blast on the right.

Some came up.  It is interesting to note that what pulled up was the black from under the tape and then I was able with additional taping and pulling to spread the area that came up.  Now this is after only 12 hours instead of 48.  I will try after 24 and see if I can continue to pull it up.  Interesting that it only came up in one area and the others were solid when I tried to pull it off.

The imperfection on the right is some lint that got on the card when I was blasting.  It is not from the primer.

John