Are Brodak and Sig thinners compatable.  I know its best not to mix, but I ran out of Sig and I have enough Brodak to finish.  No local hobby shops have any Sig,  I would have to wait for another order to come in.   Local hobby shop owner (that sells only Brodak) told me they are compatable because they are both butyrate.

I would not chance it, its thinner, yes both for butyrate, but it can be different chemsitry. better to wait a couple days and be sure, than to take a chance and spend two weeks fixing it, or years regretting it..

   Hey Mark, thanks.  I was hoping you would reply,  I been reading this forum long enough to respect you opinion.  I kind of though you would advise against it.  I will wait for the Sig thinner.   
   But here is another dilema with this project.  So far it's all Sig dope from the base up.  When I started I chose Sig's brite green as one of the trim colors,  I like the color and had some from a previous job.  Wasnt sure if I had enough so l was going to get some more when I ordered the thinner.  Sig tells me the brite green has been discontinued.  Brodak also has a brite green and on the color charts they look the same.  Thinking about adding some of the Brodak brite green with the Sig brite green I have left and using all Sig thinner.  I feel like there would be less risk by supplementing with the Brodak "pigment" so long as its thinned with the Sig thinner.  Or what about using only the Brodak green with the Sig thinner.   What do you think?   A, B, or neither of the above..     

I go along with Randy on this one. NOw as an alternat thought, do you have enough of the Sig green to cover your trim area with ONE coat? If you do, then perhaps you can spray your trim area with some Sig yellow or white first, then one nice smooth even coat of the green and it will cover over the white or yellow.
I would definatly !! use the same thinner even if you do go with the Brodaks green color. I dont think that I would mix Sig and Brodaks together, i would rather  see you use JUST the brodaks dope if my alternate suggestion wont work for you. Of course if you feel adventruous, you could buy some Sig yellow, and some Sig blue ( or maybe even a different green as a base) then mix your own green.
hope this helps you with your dilema?
And , I thank you for your kind words,,, It really is nice to be appreciated! 

Allan,
I may have some Sig Brite Green in the dungeon.  If you are interested it is yours for the cost of shipping.  I will check and drop a line tomorrow.
John

Thanks John,  I appreciate the offer.  Let me know what you have if any. 
4oz might do it for me, I would be more comfortable with 8oz.

Mark and Randy:  couple of more questions for the experts.

1>Final wipe down before spraying,  do you guys use a degreaser. 
I was wondering if alcohol would be OK as a substitute for the real stuff.  PTG in his finishing article in MA,  said he uses Windex.  Dont think he even mentioned degreassers. 
 
2>Tack rag,  I think common practice is using the tack rag last thing before spraying.  I was concerned that some of the sticky substance [whatever it is] my transfer to the surface, even though you should only use very light pressure.  Would it be better to use tack rag before the final wipe down with degreasser.

I’ll chime in here and probably ramble for a bit so you might want to grab you favorite drink.

When it comes to painting cars, I don’t know much about the whole spectrum of products and their application.  These days since I am sorta retired I do spend a lot of time watching car painting videos and talking to the guys who are doing the really cool graphics on cars.  I really like the way they just take a scalpel and cut a stencil right on the car!  Wish we could get away with that on airplanes!  The car guys have two big advantages to us model types.  First they don’t have to build the cars.  Second they don’t care about weight.  Two weeks ago my head exploded from TMI re. car painting and associated products.  Now I’m in recovery and my TMI is in remission. 

Now degreasers and wax and grease removers.  Mark points out a distinction between the two.  Maybe there is a difference but for me the results are pretty much the same.  The one thing that comes up over and over for both model painters and car painters is the need for a clean surface.  Funny how soap and water of some sort is always the recommendation by the car guys.  Clean the surface before painting.  In the past whenever I have had instances of fish-eyes or other paint adherence failures they could always be traced back to the use of any of the three products which I have tried (Prepsol, Acryli-clean, and M600) as the last cleaning substance used.  Now maybe that just me but its my airplane!

Try this experiment if you dare.  Just before you’re ready to paint put some oil or grease on two wing panels.  Use you favorite degreaser or wax and grease remover to clean one side and just plain original Windex on the other.  Now paint and just live with the result!  Don’t blame me; I’m just the messenger. 

By way of a more practical test here’s a short story to illustrate. 
Back in my avid combat days, I viewed cleaning an airplane as silly.  Unfortunately, after many flights the gummy build up would force me to submit to cleaning.  All my planes were covered with some sort of plastic (Monokote, Fascal etc.) so the oil was on the surface.  My substance of choice at first was a degreaser.  It would usually take two or three cleanings to remove most but never all of the oil.  I could always see a thin film on the surface.  One day I grabbed a can of Spray Away glass cleaner that had been rolling around in my car for a few months and used it to clean some of the sticky things.  Surprise, they got squeaky clean with the same two cleanings.  Fast forward, today I still use the Spray Away to clean my finished planes after flying however its foaming action evaporates to quickly for cleaning when painting.  Hence, Windex does the trick better.

The whole thing comes down to emulsification, which is the suspension of dirt and grease in a substance that does not mix with them.  My experience with degreasers is that they do in fact mix with grease and can actually leave a thin film of the very substance they purport to remove.  The term soap is a bit misleading as soap is lye based.  Windex is a detergent formulation, which is chemical based.  Modern detergents are the result of companies like Proctor & Gamble and Johnson & Johnson taking on the gigantic task of pleasing millions of homemakers, mostly women.  They had to get it right or….(we all have our stories).  The other really interesting thing about the Windex way is that since it is a very good detergent it also causes dust from sanding to be suspended and subsequently removed from the surface when wiped.  I paint in my garage, as do many modelers.  I plop my paint stand right next to the bandsaw since it is the place with the most light.  I clean the garage about every three years.  What I discovered many years ago is that most of the dust on our airplanes is there before we paint.  Very little comes from the air unless there is massive air movement.  Hence the idea of cleaning with Windex at least two times.  Finally, after the Windex cleanings the tack rag is used to remove lint from paper towels I use for cleaning.  The best tack rags I have found are called “Surgical Blue” and they have a less aggressive tack adhesive than the typical hardware store variety.  Buy them at the auto paint store. 

Hope this helps
Rely on the fact that something is working to validate the fact that it does work.

I'll reiterate what Mark said. I've done some finishes with urethane basecoat/clearcoat. Almost any sort of cleaner will take off basecoat. The stuff is almost all toner with no binder to speak of and no hardening agent. Even isopropal alcohol will take it off. Even Windex will take it off, though not quickly. With this stuff, I basically had to paint, use a tack rag, then shoot some clear on. Most anything will disturb it. I don't even want to tell you what masking tape adhesive does. So, shoot color, tack, then shoot a very thin coat of urethane clear. Then shoot trim color and a thin coat of urethane clear (ad nausium). Not fun.

But I use a home brew Windex to clean now. Works fine.

Since there is discussion about Windex with dope finish, I thought I would show what happend when this inexperienced person used it to wet sand the clear on a small model. I had used it with success on previous models and have no clue what really happend. The saga started when I was wet sanding the clear in preparation to apply some ink lines. The base color was white and I was using all Brodak products. I sanded the model and set it aside till the next day and when I saw it in the morning I was shocked to see this rust type of color on the model. I thought it may have been something in the sand paper so I changed that and saned with windex till that was removed and set the model aside till the next morning again. The next morning it was even worse, So I shifted to plain water and sanded as much as I could off and painted the model red. Since shifting to only water with wet sanding I have not seen this issue again. The only thing that changed was a fresh batch of windex was used to wet sand. Hopefully you can see what I am talking about in the picture.

Now my new struggle is orange peel.
Regards
Robert

Use you favorite degreaser or wax and grease remover to clean one side and just plain original Windex on the other.  

Hey Phill:
Is there anything magic about the "original Windex" brand, or will the generic / store brand window cleaners work?
The one I have now is [streak-free] and [with ammonia].   Does the ammonia cause any issues that you know of?

Hi Bob

The picture was after I sanded most of the clear and some of the white off the model. I did not wet sand the cowling and I was trying to show the difference, but the picture did not really show that. When it showed up I had had the color on and 4 coats of clear and I wanted to smooth the surface and put some ink lines on. I really do not know what happened or why, but just wanted to share my experience. The model was first painted with silver then white and I only ran into the problem when I got to the clear coats. I had painted two models without this problem using the same basic methods just different colors and I did not see this effect on them, so imagine my surprise when it showed up. I was glade it was on a little Perky and not the Strega. I had used it to wet sand the colors also, but did not see the discoloration until the clear was applied and the discoloration sanded off with the clear when I switched to water.

Regards
Robert

I'll reiterate what Mark said. I've done some finishes with urethane basecoat/clearcoat. Almost any sort of cleaner will take off basecoat. The stuff is almost all toner with no binder to speak of and no hardening agent. Even isopropal alcohol will take it off. Even Windex will take it off, though not quickly. With this stuff, I basically had to paint, use a tack rag, then shoot some clear on. Most anything will disturb it. I don't even want to tell you what masking tape adhesive does. So, shoot color, tack, then shoot a very thin coat of urethane clear. Then shoot trim color and a thin coat of urethane clear (ad nausium). Not fun.

But I use a home brew Windex to clean now. Works fine.

Hi Randy,

When painting many full-scale airplanes I shoot as many colors on one airplane as I do on models.  Using the Sikkens basecoat/clearcoat system I can get as many as four different colors on (including trim) in one day.  I shoot the first overall basecoat color on, and wait the amount of time it takes to clean the spray gun then go back into the booth and mask directly on the basecoat (recommended procedure by Sikkens and accomplished in their hands-on school), then spray the first trim coat, and repeat the procedure for the subsequent trim coats.  Actually, Sikkens recommends 15 to 20 minutes dry time for the basecoat prior to masking.  The spray booth normally runs at 70 to 80 degrees F and typically 40% to 50% RH.  I use only 3M green or blue fine line tape (depending upon how tight the curve is and how long the straight run is) and have never had an adhesion problem.  The basecoat is not marked at all by masking directly on it after 15 minutes dry time.  I'll admit that until I did this at the Sikkens school I was not a believer, but doing it made me change my mind, and it increased production significantly.  Usually, due to running out of time after putting on all these colors in a day, I would put the clear coat on the next day.  Lightly using a tack rag on the basecoat has not been a problem.  I do use the blue tack rags as the gold ones have too much tack for basecoat and can transfer the non-drying varnish used as the "tack" agent.

Also, I agree with Mark...I'd never cut a stencil directly on the surface of the airplane.  For one thing, scratching the aluminum skin has structural implications.

Bill

Randy,
one thing to keep in mind is that while you use Urethane toners in a dope clear carrier, I think Bill is using the full on urethane base color system. In that, the base colors are far less prone to tape tracking, though pearls and metallics still certainly are prone to that problem and a coat of lightly thinned clear is a good insurance policy.

ok I will go back to sleep now,, sigh,,