Observations on Stewarts System

Thanks 'Hardtailjohn' and 'Algonquin' for the info - it seems that high humidity is not really a factor other than prolonging the drying time due to slow evaporation of the water carrier. However is there a problem with colour coat blushing as with some solvent based finishes? I assume not.

Frank

I've never been able to get it to blush, and I've used it since the mid 90's.
It's tough for some people to think about how a waterborne works. Water is just the thinner/carrier, so it's taking the place of the solvent in "regular" paint. Right off the bat, it's going to dry slower in most instances. When it's cool and humid it's going to take quite a while, compared to hot and dry. I've shot this stuff in booths over 90 degrees with some high humidity (Sun n Fun for instance) and it worked flawlessly...just took a while to be ready for the next coat. With any polyurethane (and enamels in general) it's not a matter of "it takes this many minutes to be ready for the next coat". That can work fairly well with solvent borne paint, as the solvents are quicker to dry and react less to temperature and humidity (to a point), but especially for a waterborne, you have to test the surface of the previous coat to see if that paint is ready to accept more paint. You do that with your knuckle, touching the surface of the paint. Don't press hard and don't barely touch, but touch it gently first and see if there's any paint on your knuckle when you pull it away. If there is, then you need to wait. If it's still sticky but no paint transfers, you're ready to lay the next coat down. If it's NOT sticky, you've waited too long and need to let it dry 24 hours and go again. It's going to take longer with a heavier coat so after the first your dry time is going to increase. I've had to wait an hour before the next coat was layed down when the heater quit. If you rush it, it's going to end up with solvent pops and a host of other things. I can't be in the paint booth between coats or I wind up rushing and screw it up. I have a clock in the booth by the door and I take note of the time when I'm done, so I have a general idea of when to come back, but that's only the preliminary...you have to monitor the surface to know when it's ready. Airflow, heat, and humidity are big factors.
Hope that helps.
John

Thanks Hardtailjohn - My interest in using this is increasing but nearest distributor is in Holland.
Also need to check on 1956 colours being available.
Frank

Marty57 said:

It does say that, you are correct. The mixture is 3parts ekobond to 1 part distilled water. Easy to apply.
Marty

Click to expand...

marty for filling the weave isnt the mixture the other way around??? better add this is from post 23. went to stewarts system website and opened up the manual and its always in japanese or something, never been able to get it to work.

tempdoug said:

marty for filling the weave isnt the mixture the other way around??? better add this is from post 23. went to stewarts system website and opened up the manual and its always in japanese or something, never been able to get it to work.

Click to expand...

Hmmm, not sure why the download won't work. You should be able to download it from here:

http://www.stewartsystems.aero/support.aspx

The link is about three items down the downloads on that page.

In any case, I posted the reference from the manual below.

Marty

Sealing the Weave
Before EkoFill (E620) can be applied, the weave of the fabric must be sealed
with EkoBond (E610 or E610L). (To simulate the look of cotton fabric on the
inside of the aircraft use EkoBond Linen (E610L) to seal the weave.) In the past
EkoFill was used to seal the weave of the fabric, but we have found that using
EkoBond is both easier and provides better adhesion. It is acceptable to seal the
weave with two brush coats of EkoFill (E620) brushed into damp fabric as was
done in previous procedure manuals. However the following method is
recommended: Prior to applying EkoBond to seal the weave, the fabric should
first be cleaned. Dust should be removed with a vacuum or compressed air.
Next the fabric should be cleaned with EkoClean (E670) diluted at a 15:1 ratio
applied with a spray bottle and a sponge. The fabric should then be rinsed with
clean water. Allow the fabric to dry completely. The fabric is now ready for
EkoBond application.
Dilute the EkoBond with distilled water at a ratio of 3 parts EkoBond to 1 part
water by weight. Apply EkoBond to the fabric with a foam brush, being careful
not to miss any area. Only one coat is necessary, but may be brushed in
multiple directions to ensure complete application. Do not wipe off excess, but
allow to dry. If the foam brush begins to shed small pieces of foam, use a new
one. Is is not necessary to apply EkoBond over areas that have been glued with
EkoBond. Once EkoBond is applied, allow it to completely dry for approximately
30 minutes to 1 hour. It will be susceptible to dust and dirt because EkoBond will
remain somewhat tacky even when dry.* Once the fabric is sealed with EkoBond
and dry, EkoFill should be applied as soon as practical to prevent dirt and dust
build up. It is acceptable to store parts for a long period of time once EkoFill has
been fully applied, but care should be taken to keep it clean and dry. If the parts
are to be stored it is advised to not sand the final coat of EkoFill until ready for
topcoat. When ready for topcoat, wipe with a rag lightly dampened with Isopropyl
alcohol prior to sanding. If the cleanliness of the surface is still in doubt, you may
add an additional coat of EkoFill (E620) or EkoPrime, (E75XX) prior to top
coating.
*EkoBond will remain tacky indefinitely. It is possible that in areas where airframe
structure is close to the backside of the fabric but not touching, if the fabric is
pushed in to make contact with the structure it may adhere to it, which may be
considered a cosmetic flaw. If this is a concern, it may be prevented by applying
a small area of EkoFill into the weave of the fabric first in the area where it might
make contact so that no Ekobond is exposed on the backside of the fabric.

Hi, we are on to our second Supercub using Stewarts and love it. The first one is three years old and still looks as it did when it rolled out.
Today I came to apply some Eko Prime, from a can we purchased in August last year and have only just opened. The paint flowed very slowly through the filter, and when I got sick of waiting I tipped it back into the tin. When I ran some water to clean the paint from the filter I found some very fine granuals in the bottom, and that was what was blocking it. I did the test again with a different can from the same batch, same result. I did the test again, this time with a can that is 20 months old, and the sample was clear, and the paint flowed through the filter fine.
Has anyone had similar experience or tips?

Funny, I was just using some 6 month old EKo Prime today and the solids had settled in the bottom of the can real bad. Took about an hour to get it mixed, maybe you didn't get it mixed enough??

Thanks Bearhawk, I mix it until I can feel the ridges in the bottom of the can with no lumps

cheers Bill

The solids are out of suspension. Has it been frozen? Are you mixing with a stick or what? I've used OLD Ekofill before and brought it back from the dead, so to speak. It can take a while to get it all mixed back in. I made a mixer from a 1/4" rod about 2' long with 5 links of chain on the bottom, with the rod welded to the center link. Slow speed on a drill press or cordless drill and it comes back to life.
John

Hi John, it lives in a cupboard that varies between 60 to 90 degrees. The old paint has been about 5 - 10 degrees warmer and is fine. When I was filtering it to paint the room temperature was 75 degrees. I Mix with a flat stirrer that is stainless steel encased in plastic, so it is quite stiff.

Chees Bill

I'd say keep stirring. I've never had it go that bad. Most of the time, I use a rock tumbler to mix all my stuff right in the can. Put the can on and let it turn for a day or so before I need it. Seems to work well. Sometimes the solids can be stubborn to get back in suspension and Ekofill is a very high solids product. Have you called Andy about it?
John

Thanks John, I emailed Andy and he offered to replace it without hesitation, as I thought he would
Its the first time I’ve had any trouble, even when using over two year old paint on non-Aviation stuff.

cheers Bill