Frustrating Dope

Stuka Stunt Main Forum · 34 of 34 known posts recovered

Peter Hess · May 28, 2001 10:48 AM

No, this is not intended to be an autobiographical piece. It is, in fact, a question about a frustrating problem I am having with dope.
The problem is one of separation of pigments, resulting in streaky color on the plane.
I am using Brodak Ag Cat Yellow as the main color on three planes. Since I do not have spraying equipment, I have to brush on everything. I have used nothing but Brodak products, even for cleaning brushes. The paint has been very thoroughly mixed before each use and carefully thinned to get the best combination of flow {without runs} and drying speed {without premature setup}. While painting, the container is stirred about every two minutes. Even while stirring, one can see swirls of white in the yellow.
Knowing that yellow in general has low opacity, I applied a base of white before applying any yellow. The white base coat was wet sanded with 600 paper, tacked, and wiped with alcohol before applying the first coat of yellow. The same was done between the first two coats of yellow. As far as I know, either I have done most, if not all, of the right things or done nothing wrong.
I am about to apply the third and, I hope, final coat of yellow. Before I do that, however, does anyone have a suggestion for eliminating or minimizing the amount of streaking? A magic bullet would really be appreciated.
When all is said and done, maybe I am the frustrating dope for choosing to apply yellow with a brush.
Thanks for any suggestions you might have.
Peter

Jake · May 28, 2001 11:05 AM

#1 source

It is called spraying. Yellow is one of the hardest colors there is to apply by brush and have it look decent. I long ago bit the bullet and bought a compressor (two actually, one for the airbrush) and GOOD spraygun. You'll be glad you did in the long run.

JAK

Peter Hess · May 28, 2001 02:35 PM

#2 source

Jake:
Thank you for your response. Somehow I just knew that your answer would be either the answer or, at least, among the answers.
Even though I am not aware of it, I must have Scotch ancestors via Vermont or New Hampshire. I am a yankee skinflint who rubs two nickels together and will not spend one of them unless I can "justify" it. For the immediate future, the HVLP system that I covet cannot be justified.
But, surely, spraying is not the only answer. Would the streaking be helped by vitamin C or a tax cut or some other elixer?
Oh, please, won't someone send me his magic?
Thanks, anyway.
Peter

LNeumann · May 28, 2001 03:05 PM

#3 source

Your tax cut was just approved by congress and the rebate that you will get this year will fun your airbrush and compressor. Your purchase of the airbrush and compressor will be spent seven times over by those who receive it. This, in turn, will invigorate the sluggish economy and pour more money into the system. And so, in one fell swoop, you will be doing our country a vital favor by purchasing that airbrush and compressor with your tax releif money.

Tell yourself that.

Tell your wife that.

Keep saying it over and over, "I must buy this spray equipment. My country is dependinng on me. I must buy this spray equipment...."

Leonard Neumann

Peter Hess · May 28, 2001 03:45 PM

#4 source

Ah, Leonard. You rose to the bait, as it were.
I will keep repeating your mantra, but I will avoid doing so while clicking my heels with my eyes closed lest I find myself in Kansas.
I will take your response as an endorsement of Jake's implied response that there is no other viable solution and that it is I who is the frustrating dope.
Thank you (I think).
Peter

Jake · May 28, 2001 03:55 PM

#5 source

LAST EDITED ON May-28-01 AT 03:57 PM (EST)

Thin the dope with a lot of retarder (mostly) and thinner mix, and use a BUNCH of thin coats. Wet sand every other one with 600 grit paper. Rub it out with 3-M "Finesse-it II" finishing compound, then put on the clear, and rub it out again... You still won't be as happy with it as if you sprayed it.

Jake

greatcircle · May 28, 2001 08:21 PM

#9 source

>Your tax cut was just approved
>by congress and the rebate
>that you will get this
>year will fun your airbrush
>and compressor. Your purchase
>of the airbrush and compressor
>will be spent seven times
>over by those who receive
>it. This, in turn,
>will invigorate the sluggish economy
>and pour more money into
>the system. And so,
>in one fell swoop, you
>will be doing our country
>a vital favor by purchasing
>that airbrush and compressor with
>your tax releif money.
>
>Tell yourself that.
>
>Tell your wife that.
>
>Keep saying it over and over,
>"I must buy this spray
>equipment. My country is
>dependinng on me. I
>must buy this spray equipment...."
>
>
>Leonard Neumann

Mr. N.; Tried that:showed the post to the good frau Circle. She sorta smiled, and said "DON'T TRY THAT, It won't work!" What's plan B? CC

Larry F · May 28, 2001 04:55 PM

#6 source

Peter --

As I type this with my spray painted polar gray fingernails flashing in the sunlight, I can't imagine why your yellow shows swirls of white when you stir it. Doesn't make sense.

All Brodak colors stir up right nicely, and never have streaks in the jar. I am kind of a red, blue, green kind of guy, so I don't really know from yellow.

Yeah, spraying helps most everything, and is a heck of a lot of fun. But the streaks? That is your clue, and I don't think spraying is the fundamental solution. Something is wrong with your dope! Unclean cans, or something. If plain stirring still shows streaks in the jar, there is a major problem with the dope. Can't even imagine what. You should never have streaks in the jar, regardless of the color.

Larry F

denlip · May 28, 2001 05:18 PM

#7 source

A scottish sprayer. Take 2 pieces of brass tubing solder them at a 90Degree angle about 1/8inch apart. Stick one of the pieces into your thinned paint and blow like crazy out the other. Sorry I just couldn't resist it

bb36dd966 · May 28, 2001 06:49 PM

#8 source

I am using Brodaks Lemon Yellow on a Nobler and Insignia Yellow on my Barnstormer. Yellow has got to be next to black, my most frustraing color. Never put them on with a brush. Go to Lowes or such and get a $198.00 3 HP 10 gal spray compressor. Get a good spray gun. Mix 20% retarder. Got to use retarder with yellow, it goes on smoooth. Now, buy a paint stirrer from Micro Mark. They be cheap, Laddie. And they do mix the paint thoroughly. Pour half in an empty jar and mix the two separately, then box them back and forth. SPRAY the paint. Or go to blue or another dark color.

Steve Helmick · May 30, 2001 07:15 PM

#10 source

Unless you are doing detail work or very small models, you don't want an airbrush, you need a touch-up gun or a full sized spray gun, or both. You might try one of the "mock spray cans", where you add your own paint and either pump it up or attach an aerosol propellant can. Pretty sure you can get good ones at auto paint stores, and Harbor Freight has an "El Cheapo". Tower Hobbies may also carry them. Steve

Tim McTigue · Jun 01, 2001 04:16 PM

Spray gun alternative#11 source

I haven't tried it yet, but I bought a Preval Spray Gun, which comes with a can of aerosol, sprayer and jar, for about 7 or 8 bucks at Home Depot. I've heard good things about this from other modellers, and if all goes well, I'll be using it for the first time this weekend. I'll let you know how it goes.

Tim

Peter Hess · Jun 02, 2001 07:09 PM

RE: Spray gun alternative#12 source

Tim:
I will be interested to hear about your experience with the Preval unit.
The experience I have had so far with mine has been less than successful. I tried to spray Sig Lite clear that had been thinned 1:1. That mixture resembled water more than it did dope. For the first 15 or 20 seconds it seemed to work OK. After that, however, the propellant can became so cold that I could barely hold it and the dope started hitting the surface in little globules rather than in a mist. The result was a rather pebelly surface. Fortunately, it did not take much effort with wet 600 paper to level things out again.
So, let us know how it works for you. And, if anyone else has tried one of these things, how did you use it and how did it work?
Peter

Jake · Jun 02, 2001 07:28 PM

RE: Spray gun alternative#13 source

The answer is it doesn't. You CAN'T go cheap...
If you want a decent, long lasting, good looking finish on your models, you HAVE to be willing to part with the $s, otherwise, you AREN'T gonna get there, PERIOD!
I know it full well. How much are your time and efforts worth?
If you don't value yourself very highly go cheap. But in today's world, either do it the very best way, or quit right now.

JAK

Peter Hess · Jun 02, 2001 08:09 PM

RE: Spray gun alternative#15 source

Jake:
I do appreciate your sentiments. I am very much in the (re)learning stage and am the kind of person who has to learn things for himself one step at a time. But, I can and do learn. Proper spraying equipment will find its way into my basement in due course. However, in the meantime, I am certainly not going to let a less than perfect paint job detract from the pleasure I have gotten out of trying and that I will get out of flying the planes. The next one(s) will be better and each one will be the best that I am capable of at the time and with the equipment then available.
For a number of reasons - - only one of which is the streaky yellow - - it is now clear to me that getting good spray equipment will be necessary to produce the results that I want. But, even having realized that, I am unable to forget the immense fun that I and my flying buddies had decades ago when "finishing" consisted of three brushed coats of unthinned clear followed by a couple of brushed coats of unthinned color dressed up with a couple of stripes.
So, I appreciate the generosity and patience of folks such as yourself who take time to encourage and counsel those of us who still have so much to learn.
Peter

Gary Widmer · Jun 03, 2001 11:14 AM

#16 source

The latest Harbor Freight catelog has a 3hp, 10 gal compressor for $169.99 item #38795-2RKA. Gary

Peter Hess · Jun 02, 2001 07:41 PM

#14 source

Larry:
Thanks for your comments. I, too, at first thought that it was a bad batch of dope or that I had contaminated it somehow. However, I have discarded that theory. I bought two four ounce jars and a pint can. (The pint might have been enough, but I wanted the jars.) I started with one of the four ounce jars. After seeing the first evidence of the problem, I tried the second jar and got the same result. Then, of course, I tried the contents of the pint can and, surprise, same result. There is, however, some hope (see below).
JAKE:
Thanks for your suggestion about using a "bunch" of very thin coats. Although I thought that I had thinned the dope to an appropriate consistency, in response to your suggestion I decided to see just how thin thinned can get and still work. Well! Brodak Ag Cat Yellow will handle a lot of thinner. I am now using a mixture of about 1.5:1, thinner to dope. Up to a point, the stuff seems to get better the thinner it gets. It seems to carry and dispurse the pigments better. When I posted my message, I had two yellow coats on the planes. I now have four and even before sanding them the color seems to have evened out considerably even though it is still a bit streaky. After sanding, I will try two more very thin coats. If after that the pigment density/thickness is still not sufficient to eliminate the streaks, then I will have created a signature marbled yellow finish.

Peter

Tim McTigue · Jun 03, 2001 04:28 PM

#17 source

Peter,

I very much like your attitude! It very closely mirrors my own. I've been working away at this hobby since last August when I built a couple of scratch-built half-A planes. Since then I've built a Skyray and am putting the finishing touches on a Flite Streak - both scratch-built from plans. I've made many mistakes along the way, some of them would cause "serious" modellers to shake their heads and sigh, but I have to admit I'm still having a blast. Hardly a day goes by that I'm not thinking about what I want to do next, and I'm in my workshop at least 10 hours a week. I've only been out flying about 4 times so far this season, but I can tell that once I get to do that fairly regularly, there'll be no getting me away from my planes. I know that as time goes by I'll get better in my technique, and my tastes will become more demanding, and I'll tend to get better tools and materials, but for now, what I'm doing is just fine for the level I'm at.

BTW: In your last post, you mention thinning the dope to 1.5:1 - is that still with the Preval unit, or have you moved on?

Tim

Peter Hess · Jun 03, 2001 08:12 PM

#18 source

Tim:
I have moved back - - to my brushes, that is - - not on. I will experiment a little bit more with the Preval unit after my planes are done. However, based on my first experience with it and on the fact that nobody has jumped into this thread to say how great the Preval unit is, I hold out little hope for the Preval. However, do not let that discourage you from at least trying it. I would suggest, however, that you not do it on a plane.
Peter

Steve Helmick · Jun 03, 2001 08:37 PM

#19 source

LAST EDITED ON Jun-03-01 AT 11:17 PM (EST)

I'd guess that your problem with the Preval spray unit was from the cooling aerosol can. Look for a way to solve that problem, either a way to heat the can with a pan of hot water, a heat gun, or some kind of heating pad. Hot water sounds like the safest way, but you'd need to keep the water away from your model. Keeping the temp of the aerosol can up will of course keep the spray pressure up. Steve

Randy Ryan · Jun 03, 2001 09:51 PM

#20 source

Peter,

The one question I haven't seen in this thread is: what is the width of the brush you're using? Too narrow a brush will give you fits because the tiny area covered will be so uneven in thickness that it will actually look streaked.

Tha other thing is the white under the yellow. You'll need to get the yellow on very rapidly to keep from forcing the white to bleed up into the yellow as you brush. You can't spend time with a skinny brush trying to flow it out, you need a wide, soft brush that you can move quickly with. Also, when your brushing lacquer type coatings, all the fine sanding is pretty much lost since the brushing rearranges everything under it. You need to get the finish built up, then sand even finer (1500) and rub it out. I don't mean you don't sand, but the process is different for brushing then it is fir spraying.

Last, try putting a quick cost of clear on then the yellow, this may seal the white down.

Any time you put one color over another with dope you need to move fast, that's really why spraying is ideal. I spray now, but I brushed for years and have always had people ask how I get my finishes.

Randy

Currell · Jun 03, 2001 11:06 PM

#21 source

Re Preval: I used it on one plane with pretty good results: silver on a Hurricane. It doesn't put out a lot of pressure, however. You end up holding the spray head close to the surface.

Brush thickness could be a factor, as previously stated. I like the 1" jobs Sig sells.

Currell

Tim McTigue · Jun 15, 2001 04:10 PM

#32 source

I, too, am now moving back to brushes, after trying the Preval.

What I like about it:

a) It's cheap
b) The jar has its own cap, so you can save a mix for later
c) Not much else

What I didn't like about it:

a) Very difficult to get a nice even coat
b) Not much pressure
c) Not enough aerosol propellent to do much (not enough for a plane)
d) Can gets cold while using it
e) Come to think of it, it's not all that cheap...a new can of propellent costs almost as much as the full kit
f) ...(you get the idea)

Tim

PS: Currell, you said you used it on a plane. How many cans of aerosol did it require?

carigotti · Jun 15, 2001 08:52 PM

#33 source

Tim,
I used Preval painting my Legacy 40 fuse and fin. It worked OK but noticed that same problems. Propellant ran out quickly and the can got very cold. I got mine at the local Sherwin Williams store. I lucked out as they were having a sale like 30% off everything in the store. So I got like 4 units. I have since ordered a Badger 350-4 airbrush kit. this is supposed to spray from like 1/4 to 3 inches wide. I use Monokote on the wing, flaps, stab, and elevators and only paint the fuse, fin and rudder so I thought an airbrush would be big enough. Anybody use an airbrush on their fuselages?

Crist

bb36dd966 · Jun 04, 2001 07:06 AM

#22 source

Hi Pete. Seems you have gotten a lot of good advise. When I paint one color over a different one, I always cover the first with clear. If I brush, I use at least a one inch brush, the most expensive ones I buy run around $15.00 each. They be worth it matey. When I spray, I use a 3 HP, 10 gals unit at 20 to 25 psi (experiment here) and use a 8 oz touch up spray gun. I sometimes say spray brush as I use them too, but for the planes a spray gun. Brodaks will and does take a lot of thinner. It is a very high quality paint. When brushing , use short, steady strokes and go only one way. Be sure to load the brush with lots of paint. Going back and forth will create a drag on the paint and it piles up and will at times pull the bottom color into it. Thus the streaking. Try the battery powered paint mixer from Micro-Mark or a hobby shop. It gets the bottom pigments mixed. This is the longest part of any paint job, the preparation. Be sure to mix thoroughly and them mix some more. And of course, practice, practice, practice. If you are in the basement as you mentioned, PLEASE, use lots of ventilation. This means fresh air coming in near you and all those fumes leaving the house. This is more important than you may realize. Getting goofy on those fumes will make the paint job a mess and you just won't care. Heck, you just may be out cold.

Gary Widmer · Jun 06, 2001 10:12 AM

#23 source

Where do you get high quality brushes? My old red sable brushes are shot and I can't locate replacements (at any price). I tried the SIG 1" camel hair number and was underwhelmed, to say the least. Gary

Flyin_Again · Jun 06, 2001 12:02 PM

#25 source

I just got some Torrington brushes and they are great! I was tired of picking hair fibers out of my dope finishes and so far the Torrington 3/4" & 1" are perfect.

Check out their website at http://???.torringtonbrush.com. The prices are reasonable too. Very nice people to do business with also!

Have fun and keep-em flying!

Bill

Peter Hess · Jun 06, 2001 11:32 AM

#24 source

Thanks, again, to all of you who have taken the time to offer advice. Special thanks to Randy and bb36dd966 for very specific suggestions that match my circumstances.
I have used, variously, 3/4" and 1" camel hair brushes of the Sig persuasion. Based on what you have said, I think I will use the 1" exclusively.
I have kept the brush full and flowed the dope on in one direction only, with occasional overstrokes to smooth out obvious unevenness and/or avoid an impending run.
The suggestion about sealing the undercoat with a coat of clear sounds like a very good idea. In fact, I have already taken the suggestion and added a coat of clear to two of the three planes. Since the purpose of doing that is to minimize or prevent mixing of the overcoat with the undercoat, I am giving some thought to adding, and then sanding, a second coat of clear before trying additional coats of yellow.
Finally, your advice about ventilation while in my dungeon is very well taken, indeed. In fact, I have fabricated a false door with a cut-out for a 24" fan that I place in the door frame of the basement door and run while painting. The fan draws a noticeable volume of air from the house and through the basement. In addition, I wear a fume mask with dual replacable cartridges. It is, however, always good to be reminded of the importance of such things.
Again, thanks to all. I will report on the results of using the clear blocker.

Steve Helmick · Jun 06, 2001 07:12 PM

#26 source

LAST EDITED ON Jun-06-01 AT 09:43 PM (EST)

"Check out their website at <http://www.torringtonbrush.com>. The prices are reasonable too. Very nice people to do business with also!....Bill"

It is NOT necessary to obscure a suitable URL. The software is not set to delete them, and Leonard is not inclined to...also "Very nice people to do business with"!

Seems to me that spray equipment is not all that much more expensive than a few red sable paint brushes! I also don't think it is terribly important to buy the finest, because you are going to sand away the bumps and runs anyway, aren't you?

EDIT: Bill, I went to the Torrington Brush website, and you can order online, but the full catalog does not appear to be available online. However, there is a list of brush types/uses. There are brushes "Lacquer, Flat" (shape). Would that be the best choice for SIG or Brodak butyrate?
Steve

JAK · Jun 06, 2001 09:09 PM

#27 source

But the best LASTS a lot longer. You get what you pay for, and if you are going to expend the time, effort, and $s to build a model (add up what it costs per hour, to do it correctly, and Guys, it WILL shock you, I guarantee it!) in the first place, and you might as well do it the very best way, using all the best things you can. Remember the old proverb: "Anything worth doing is worth doing well".

JAK

Flyin_Again · Jun 08, 2001 12:44 PM

#29 source

LAST EDITED ON Jun-10-01 AT 11:19 AM (EST)

Steve,

You are right about more choices through the Torrington catalog. The brushes that I obtained were off the website and they are the flat laquering type. The numbers are 05118 for the 3/4" and 05119 for the 1" wide brush. They are made from camel hair.

I bought the best that Torrington offered as I'm tired of poor quality in products. Like others have said,"you get what you pay for"! I'm satisfied with these brushes, both in results and quality.

I hope this info helps.

Bill

joem · Jun 08, 2001 10:16 AM

#28 source

Peter,
I know where you are coming from. I brush almost exclusively and dope is the toughest to apply with a smooth finish. Poly-u and the perfect paints seem to cover the best for me.
have you tried an alternative brush, like a foam brush or a small foam roller? these might help.

TigreST · Jun 10, 2001 08:40 AM

RE: Frustrating Dope- Mixing#30 source

Peter,
Re: Mixing; In keeping with your Scot heritage save yourself the cost of the Micro-mark mixer, and use what I use. A)Take one Black and Decker 3/8" variable speed drill (hope your still not using the Bit-n-Brace?). B) Take one wire coat hanger.
C) Cut coat hanger to length of your choice, leaving enough material to put a couple curly Q's in it. Twist the ends together in such a fashion as to leave a single wire length free at the twisted end. D) Chuck the coat hanger, with Curly-Q's, into the Black and Decker. E) Test spin the mixing wand/drill unit to check for "center", and bend wand to get it kinda' on a center line axis. F)Submerge mixer in can/jar. G) Set variable speed control knob to moderate speed, lock the ""go" button in the on position, ..mix to your hearts content.

CAUTION: If your heavy on the rpm's, you'll coat the front of your shirt/pants/work bench/walls/ceiling/ etc etc. DON'T pull the wand out of the jar while it's spinning, ...but you knew that right?

Depending on the shape of the mixing wand, you can get it to scrape right along the bottom of the can/jar to kick up all the material that settles out. I've used this technique with the Brodak primer most recently, ..that stuffs got a lot of filler material in it, and settles out big time on the bottom of the cans. Once the bulk can/jar is mixed, portion out what your going to use and mix again when you add your thinners to the second jar/can.

One thing I've found is that it's surprising how long it can take to get all the paint pigment back into suspension after it's settled while on the shelf. It's not a wam bam thank-you mam mix job, it does take some time to get a completely mixed can.

RE: brushing; Yep that's how I started out as a kid. Big brush for the finish coats. But back then we did not thin the dope, it came right out of the jar as is. You will get better flow with the thinned material, but the extra thinners may increase the likely hood of attack on the under laying coats of white, ..don't know where the thinner cut off point would be in that respect?

RE: Spray Equipment: You get there one day for sure. Price and quality of equipment can be had for almost what ever you wish to pay. HDC Inc , which produces a lot of knock-off tools off shore, sell passable equipment for cheap. This winter I picked up a complete spray kit: Full size automotive spray gun: 8oz auto touch up gun: tools: face mask: air chuck adapters: carry case/ $59.00 at the yearly Armory truck load sale. It does the job, but I'll be going HVLP once the new compressor is wired in.

Tony

Nils · Jun 10, 2001 02:27 PM

RE: Frustrating Dope- Mixing#31 source

This thread is a good reminder to me that there are some advantages to working in a body shop

Do be careful with the new type car paints guys, it really is toxic.
Nils