Airbrushable primer

[GrahamB]

Hi and the Season's Greetings.

 

Wondering what people think is the best airbrush-able primer paint, particularly for etched-brass and resin? Tamiya's spray-can stuff is excellent but somewhat wasteful when doing small batches of tiny kit parts. Any suggestions gratefully received.

Cheers

GrahamB

[colin]

De-cant the Tamiya stuff and spray through your airbrush, saves a lot of waste.

[fewr9fkr9595]

Stynylrez 

[Kev The Modeller]

I've tried several, Ammo Mig, UMP and Mr surfacer all work well but are very different in the use.  

Ammo is easy to use and for me works best if thinned.  You also get what looks like shinny blotches on the surface, but it's still very smooth and this disappears completely once painted, it doesn't happen all the time or on every surface it happens on all colours, I've not tried the new one shot.   

 

UMP is very good well the black and grey are not tried white or other colours, but I've read reports they're aren't so forgiving and need thinning .  The gloss black is not so good in my opinion, applied as per the instructions 0.4 needle or bigger 20 plus psi and no thinning,  that the surface finish is almost orange peel.  I've not tried thinning it yet and I only bought it to use under metal finishes, I stopped using it as I wanted to get parts coated so switched to X1 Tamiyan black.  When I've got time I'll experiment, I think it's going to need thinning.

 

Mr Surfacer, this is a new product for me, it's a 2 in 1 primer and micro filler, comes in various grades I've got 1000 and 1500.  I got it on back of watching others use it, I've used the 1000 mixed 50/50 with Mr Hobby levelling thinner its brilliant although it does smell. 

 

As with so much of airbrushing, paints, primers etc it's full of variables and what works/suits one will not suit another, most of the main players products all work it's weather you like them.       

[GrahamB]

Many thanks for the suggestions. I guess my only no-no is using acrylic based primers (Vallejo etc) that are just too fragile to stand much handling. One problem I have in NZ is getting solvent-based paints/primers because of the severe restrictions on airmailing these things from abroad. I've just tried decanting from the Tamiya spray-can - make you realise just how little paint there is in there!

Happy New Year.

 

GrahamB

 

 

[Matt_]

Because photo-etch parts are so small, they are usually covered in little corners and edges where it's easy to rub 'coating' primers off. Water-based polyurethanes like Stynylrez or Vallejo don't bond to the surface, they just create a skin. Cellulose primers that melt into styrene will also just create a skin when used on metal. To lay down a fine, yet strong primer onto photo-etch you really need an acidic etch primer for metal. These primers eat into the surface to bond, creating a stronger finish. You can get either pre-mixed or 2-pack etch primers. The 1k ones are simpler, but have a shelf life of usually about a year from date of manufacture.

 

Or if the parts are somewhere they're not going to be touched, just paint them and be very careful handling them during assembly.

[GrahamB]

Thanks Matt, this is useful information. I remember trying an acidic primer some years ago but it was rather thick and powdery on application but I probably didn't have a thinner. One can also get fixated on the need to prime everything.

Cheers

Graham

 

a Flyhawk SMS Derrflinger on the stocks, with all the the etched "bells & whistles'.

[jelliott523]

I have switched 95% of my priming to the Stynylrez/UMP Primer which are the same thing, they are made by Badger Air Brush in the US. I typically use the black, grey, and white. I have noticed that the regular black is somewhat thinner than the grey and white and I can spray it just fine in my Badger Renegade Krome with the .2 needle at around 25psi, I do get a little tip dry, but that is likely due to the small needle size. I will sometimes also spray it through my Paasche Talon with the .3 needle. I have not thinned the black primer; however, when spraying the grey and white, I do typically add a few drops of the UMP thinner to the mix and it flows well.

As to the comment about this thinner only forming a skin on the surface and not bonding, I have to disagree. I have used the Ammo of Mig Primers (before they came out with One Shot - which btw is also Stynylrez) and it acted the same as the Vallejo primer and they would just roll and peel off the surface no matter what.

With Stynylrez, prior to spraying the primer, I will wipe down the model with 91% ISO alcohol to remove any dirt and or grime left by my hands. After spraying, letting the primer fully cure for several hours is recommended. I usually let mine sit for a good day or so, if I'm going to need to do any sanding. This primer will feather and blend perfectly without rolling up and peeling off.

 

[GrahamB]

Many thanks! This is possibly what I can get hold of  -Stynylrez/One Shot. I'll give it a try.

Cheers

GrahamB

[Matt_]

12 hours ago, jelliott523 said:

As to the comment about this thinner only forming a skin on the surface and not bonding, I have to disagree. I have used the Ammo of Mig Primers (before they came out with One Shot - which btw is also Stynylrez) and it acted the same as the Vallejo primer and they would just roll and peel off the surface no matter what.

With Stynylrez, prior to spraying the primer, I will wipe down the model with 91% ISO alcohol to remove any dirt and or grime left by my hands. After spraying, letting the primer fully cure for several hours is recommended. I usually let mine sit for a good day or so, if I'm going to need to do any sanding. This primer will feather and blend perfectly without rolling up and peeling off.

 

When I say that it forms a skin, that is not to say that it isn't stuck to the surface. The difference is that the polyurethane primers create a layer on top of the plastic or metal that is stuck like a glue. The surface itself is unaffected. An etch primer contains an acid that eats into the metal allowing the primer to key the surface for a better hold. A similar thing happens when using a cellulose primer on models, the acetone melts the top layer of plastic, allowing the plastic and primer to mix. Don't get me wrong, Stynylrez is a great product, but I'm not sure photo-etch is its forte. 

[sapperastro]

A nice, thin coat of enamel paint is perfect for primer.

[jelliott523]

3 hours ago, Matt_ said:

When I say that it forms a skin, that is not to say that it isn't stuck to the surface. The difference is that the polyurethane primers create a layer on top of the plastic or metal that is stuck like a glue. The surface itself is unaffected. An etch primer contains an acid that eats into the metal allowing the primer to key the surface for a better hold. A similar thing happens when using a cellulose primer on models, the acetone melts the top layer of plastic, allowing the plastic and primer to mix. Don't get me wrong, Stynylrez is a great product, but I'm not sure photo-etch is its forte. 

Matt, my apologies! I didnt catch the part about you referencing the metal and a primer for that. I would agree, Stynylrez by itself is not good to use on photo-etch. In this case, for me, I use Mr. Hobby/Mr. Metal Primer before doing any painting on photo-etch, even then, I've not had the best of luck keeping paint sticking. I may look for another, possibly a cheap automotive primer that I can use.

 

[Matt_]

I think that Mr Metal Primer is a cellulose base metal primer.