What am I doing wrong?

Okay, I’ve spread my scenery material down and now I’m ready to glue it in place. I have my diluted matte medium and my spray bottle. I’m spraying and things are going just great, until about the tenth spray then it just kind of starts spitting more than spraying. No problemo, I figure the pump is just clogged. So I clean it and apply a screen to the feeder hose to prevent it from happening again. So I’m spraying again and things are working just fine again until about the tenth pump when it starts spitting again. This time I blame it on the sprayer itself and by a better quality sprayer. Well after three different sprayers I still have the same problem. It seems a simple enough process so what am I doing wrong?

Mark
____________________

Ratcals Red Ale
“Can’t wait til Friday”

 

Mark, be sure and blow out the feeder hose once in awhile. Sometimes you'll get build-up inside.


------------------
"Follow the Flag"


Heck, I'll drink to that!

 

I shouldn't get a noticeable amount of buildup that quickly on a new pump should I? I've tried various proportions of water and it doesn't seem to make a difference. I can fix multimillion dollar radar, you'd think I could figure out how to spray glue.


Mark
___________

"Everyday's a good day with Ratcals!"

 

Well ratcals,
all I can say is "been there, done that"

I add some alcohol and a drop of dishwashing
soap to my mixture and keep
it thinner than maybe you think it should
be. It still will clog eventually at least it
allways did with mine especially if you stop
spraying for awhile. But I think that will
get you past ten sprays or so.
Keep at it---
SA

 

RatCals, Matte Medium is an artist's prep used to coat over and seal porus surfaces. PVA is polyvinalalcohol (hair spray) which is a water soluable "glue" usually used to hold people's hair in place once the water evaporates. As I understand it, the three are similar, but not exactly the same. I was advised to thin matte medium 60% distilled water to 40% as recieved matte medium, then to add one teaspoon isopropryl alcohol to one quart of mix, as a surfactant. (Do NOT use ethyl or methyl alcohol). A detergent is of a heaver viscossity than the alcohol, and has a tendancy to attach to the matte particulate in suspension, where the alcohol does not. Various oxides of iron and sulfides in tap water react with the copper particulates in the matte to cause a minute corrosion which then causes the particles to congregate, thus probably causing a build up to plug the tiny orfice of your sprayed. Sounds reasonable to me, and I have not had the spitting spray problem. Beyond that, I don't know either.

------------------
Watash #982

 

Thanks Watash for the info. I must admit I was beginning to suspect the “oxides of iron and sulfides” in my tap water (just messin’ with ya). Seriously though thanks for the help. It seems I still didn’t have the right ratio of water, alcohol and matte medium. I was using 1/3 of each thinking that would be thin enough. I ended up adding one more part water and it works fine now.

Later
Mark
______________

Ratcals Red Ale
"Did somebody say beer?"

[This message has been edited by Ratcals (edited 07 January 2001).]

 

Sounds like 'frothing' in the pickup tube allowing more air to be passed with the mix (now that does sound good!) causing the spitting effect. A way around it? Probably as you are doing now - removed the spray section and spray out whats in the pickup away from the layout, reinsert, then start all over.
Other than that, sorry!

Gary.

------------------
Gary A. Rose
The Unofficial TC&W page
TrainBoard Moderator and Member No.377
N to the Nth degree!

 

I put the formula into my big computer and ran the porportions. Your problem is you have been chewing the old mildewed tobacco, and that is what is making all the spitting! Add some more alcohol and enjoy!

------------------
Watash #982

 

Thanks, it is a warm feeling to be of use when you wander in the autumn of life.

------------------
Watash #982