Blocking Coat

[jfv]

Just wondering what the preference others have for a blocking coat to cover up the camouflage look after sanding.  My last several builds I have been using Sparky's recommended DC540 with Duplicolor Paint Shop colors.  I used Duplicolor Paint Shop's gray primer as a blocking coat.  Worked out pretty well.  However, on my new build I am considering trying Auto Air colors as they are water based with less VOC.  Just wondering what others are using for a blocking coat with the various paints they use.

[David Hoover]

If you're using Auto Air Colors you need to use their Sealer White or Sealer Dark for the blocking coat.  White or dark depending on the colour you're using.  They are very effective as blocking coats but may be a little heavier that some other materials so you don't want to put them on too heavily.  Spend some time on their web site reading the application instructions.  They require a little different technique than conventional paints - not difficult, just a little different.  I've done several planes with them and have been very happy.  The only thing I'm not happy with sometimes is my skill with the spray gun.

[jfv]

Thanks David.  I knew about the sealer white.  Just didn't know it would cover well enough to be used as a blocking coat.  My experience with whites as blocking coats is that you need to put a lot on to cover.  That surely adds unnessesary weight.

[Dennis Toth]

Jim,
If you have the surface ready for paint you might consider using either a cream or light gray of the paint type you will use for final paint. I don't know how heavy the water base paints are compared to dope but if the surface is sealed-water proof then the cream or Lt gray will cover and give a good base color.

With dope after initial sealing and filling, silver was used as the fine filler and surface prep. The silver is very unforgiving and shows every little imperfection (makes you feel like crap, but it is the lightest dope filler you can use for surface prep). The surface issues were filled and all was sanded down till almost all the silver was off. Some finishers gave it a second coat and sanded that off after the surface was to their liking. Then a single final coat of silver was sprayed on as the block. Some other used Cream or light gray color instead of the silver for the block coat.

Best,       DennisT

Best,       DennisT

[David Hoover]

Jim, the sealer white works fine as a blocking coat.  One thing to watch with the Auto Air Colors is that none of them except the sealers are completely opaque.   Some colours look better with the white sealer under them and others look better over the dark sealer.  The trick is to come up with a choice of colours that uses only one of the sealers otherwise you're masking for the two sealers and for all your colours.

[jfv]

My colors are red, white and black, (very original don't you think?) so the white sealer should work fine then.

[David Hoover]

You're good to go.  I used those same colours on a plane a few years ago and it came out fine.

[Avaiojet]

My colors are red, white and black, (very original don't you think?) so the white sealer should work fine then.

jfv,

I never thought I'd consider red, white and black on a model, but seeing what Robert does with those three colors, I'm convinced I can use them quit nicely on my next model. And I will.

David,

Nice looking red white and black model. 

[jfv]

Here's what I'm working on.

[Avaiojet]

jfv,

I like it!

Will you do panel lines as per your rendering?

[jfv]

Panel lines will be pretty much as shown.  I do know I left one line out on the right wing.  Already fixed on my drawing.

[Avaiojet]

What program are you drawing in?

If it's vector, it's good to go for laser cutting.

[jfv]

Drawing was done in AutoCad and all parts were laser cut.  Have my own laser.

[David Hoover]

Drawing was done in AutoCad and all parts were laser cut.  Have my own laser.

Sweet!!!!!

[jfv]

David:

How much white sealer do you think I will need?  Wing area is 502 in2.  Also, what reducer do you recommend?  I see there are 3 choices, fast, medium and high performance.  Trying to get my paint material list lined up.

I'm thinking:

16 oz White sealer
16 oz reducer
16 oz airbrush cleaner
4 oz red
4 oz black

[David Hoover]

You could probably get away with only 4 oz of white sealer since it doesn't get sanded off like most sealers - just a quick scuff with 600 or 800 grit then spray colour.  I bought 16 oz so I'd have it on hand for other projects.  I've used only the medium reducer (I think it's #4010) and it's worked fine for me.  The airbrush cleaner is a good idea - it cleans better than water and isn't was corrosive on spray gun parts.  You'll need a finish white because the sealer isn't suitable for that.  I like the Pearl White #4301.  It has a little more drama than just a plain white.  You'll be fine with 4 oz of all the finish colours but you'll need a topcoat to protect the colours.  If it's an electric rig, something like Minwax Polycrylic will be suitable.  If it's a 'wet' system you'll need something like Nelson Hobbies http://www.nelsonhobby.com clear with the cross linker if you want to stay in the low odour, low VOC vein.  If you don't mind the smell, health hazard etc. there are about a zillion other clears you can use.

Auto Air provides very good technical information on using their products and I strongly suggest that you download the information appropriate for what you're doing and read it very carefully before starting.

My experience with Auto Air Colors is not extensive but I've been very happy with the results I've achieved.  Good luck with it and above all, have fun.

[jfv]

Thought I might be able to use only the sealer white as I've seen some where the white lettering was done that way.  Anyway, I'll take your suggestion and get a white color coat.  The power is electric and I plan on using KBS Diamond Clear for my clear coat if my test piece works out.  If not, probably 2 part auto clear.  I have a friend that has an autobody shop where I can spray it. Thanks again for your help.

[Dennis Toth]

Jim,
For electric using auto clear or KBS Diamond clear is not needed. They are both heavy and since there is no fuel to mess up the finish you can use simple Krystal Clear rattle can and get a very good finish. Save the weight. On electrics the battery is the heaviest part of the ship, next is the finish. I personally like dope since it is very light and just put on a clear top coat for UV protection and gloss. Basecoat/clear coat may be another option for light weight but it is expensive and you need to be careful when applying.

Best,       DennisT

[jfv]

Dennis:

I also use dope but have fun trying other paint systems to see what I can get to work.  As I said earlier, I have been using Duplicolor Paint Shop paints with pretty good results.  My latest build is sort of a hybrid composite wing with the glass applied with EZE-Kote (water based resin). Primer is NAPA DC 540.  Was trying to get the final color done with a water based system.  I like having the clear coat at least fuel resistant since the guys I fly with are mostly into nitro and when they launch for me usually have some residual fuel on their hands.  After all this, I might go with base coat/clear coat as my friend with the body shop offered to give me what I needed.  Also, I can use his spray booth for the nasty clear coat.