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Building Tips and technical articles. => Paint and finishing => Topic started by: James Mills on April 07, 2011, 04:19:51 PM
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Okay Randy Powell, Sparky, and several others with the expertise. So here is the thing, I'm way behind (in my mind anyway) on my Junar for the Nats and am wondering how long it would take to go from bare wood to final clear with a traditional dope finish. I've never tried to finish one in a time crunch like this. I can use car clear for the final clear if necessary. I am thinking of going with an iron on finish (the wing was built int Bob's lost foam jig).
James
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James,
It's not so much the time in days to finish but the hours you have to put in on a per day basis. Normally, it takes me about a month to do a finish from bare wood to let's go flying (depending on how complex the paint scheme is). I've done it in as short as 6 days, though it wasn't much fun and was only a marginally acceptable finish from a quality standpoint. I would say that if you are able to put in a couple of hours a day and 3 to 5 hours on the weekend days and are good at sanding substrate, you could put down a decent to very good finish with a nice but not too complicated paint scheme in 2 weeks or so. 3 if you want to insure a very good surface to paint on.
Some people work faster or slower than others so the time varies quite a bit depending on the speed you work at. Normally, for a front row finish (and I've only done a couple of those), I'm looking at 75-100 hours of work. Maybe a bit more if I am doing a really complex paint scheme that takes a lot of backmasking.
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I agree with Randy. I'm not an "expert", but I have painted a few model airplanes! (and a couple were pretty nice LOL!!) Two to three weeks is very "doable" and still get a very nice finish if you can work on it on a regular, daily, basis. Gassing off of the dope is a time constraint. Sanding is the other big one! Letting the coats dry enough to sand before the next sequence is a slow process. I want the "smell" gone before moving on, which is a pretty good indicator that the dope can be sanded without gumming up the sandpaper. If you use automotive primer for filler instead of dope & talcum/zinc sterate, a day or two can easily be gained. Back masking and such can speed up the color sequence by a day or so, too. ;D
Remember, you can start flying the model as soon as the final clear is "dry". Rubbing out the clear dope final coats needs to be done a good bit later, anyway, as you already know. I know that at the '96 NATS, the final "rubbing out" of my model was done there, but I had been flying the model for quite a while.
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Hi guys,
I'm sure it takes a lot of time to do a good finish. I was just wondering if ya used a heat source, would this help speed up the process?? I'm sure its better to let nature take its coarse but I've noticed if you're good with a heat source the finish seems to have a better shine to it??? Can't you buy precut mask schemes???? Would this be cheating???? Hey!!! Don't some use a power type sander??? Could be wrong but I think Phil uses something to polish his planes???? I've been using Koveral material and it seems to make finishing quicker???? I'm sure you could get some sort of heat lamp and it would help the cure problem???? What the heck if ya got it to hot ya probably would have to start over from scratch????? The harder I look at my finishes the closer I come to throwing the hold works in the trash??? Just wondering about the heat thing, if it could help??
Gary
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Hi guys,
I'm sure it takes a lot of time to do a good finish. I was just wondering if ya used a heat source, would this help speed up the process?? I'm sure its better to let nature take its coarse but I've noticed if you're good with a heat source the finish seems to have a better shine to it??? Can't you buy precut mask schemes???? Would this be cheating???? Hey!!! Don't some use a power type sander??? Could be wrong but I think Phil uses something to polish his planes???? I've been using Koveral material and it seems to make finishing quicker???? I'm sure you could get some sort of heat lamp and it would help the cure problem???? What the heck if ya got it to hot ya probably would have to start over from scratch????? The harder I look at my finishes the closer I come to throwing the hold works in the trash??? Just wondering about the heat thing, if it could help??
Gary
I never had any luck using heat. I think its because it takes time for the solvents to migrate to the surface and escape, heat only seems to quickly dry the surface and then it softens again from the solvent below it. I have on occasion set a curing model in the car in the sun with the windows closed and left it for a day, but I'm really not convinced that did much either.
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James,
It's not so much the time in days to finish but the hours you have to put in on a per day basis. Normally, it takes me about a month to do a finish from bare wood to let's go flying (depending on how complex the paint scheme is). I've done it in as short as 6 days, though it wasn't much fun and was only a marginally acceptable finish from a quality standpoint. I would say that if you are able to put in a couple of hours a day and 3 to 5 hours on the weekend days and are good at sanding substrate, you could put down a decent to very good finish with a nice but not too complicated paint scheme in 2 weeks or so. 3 if you want to insure a very good surface to paint on.
Some people work faster or slower than others so the time varies quite a bit depending on the speed you work at. Normally, for a front row finish (and I've only done a couple of those), I'm looking at 75-100 hours of work. Maybe a bit more if I am doing a really complex paint scheme that takes a lot of backmasking.
Randy,
I'm going to be off work for a few more weeks with my knee (and I'm off all the pain meds so things make as much sense as they did before LL~). The pain meds are what put me behind, couldn't focus or think clearly. The paint scheme will not be to complicated, but I do want it to be nice.
James
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James,
with lacquer (dope) if you dry it to fast with heat, it will do just as Randy says, it will skin over, and then trap solvents. this will cause it to shrink out after you sand it, because sanding opens the pores and allows the solvents to escape. Best to build it up with reasonable coats, one in the morning, one in the evening. If you want to help dry it out, best bet is to wait about an hour after you spray it, then lightly scuff the surface open with something like 320, just enough to get a uniform scratch pattern on the surface. In fact, when I used to paint cars with lacquer, we used to break the surface about every hour to facilitate drying. moderate heat, say 80 to 85 degrees wont present problems as long as the heat is surrounding the airframe. If you expose one side to heat, and not the other, you are encouraging warps to occur. I personally never attack a model with a power sander of any sort. its way to hard to control and you will end up making the surface ripple. Better to sand with blocks, by hand. if you have done your woodwork well, its not as bad as it seems. Just work on one part till its done, then move on,, dont jump around or you will get confused and miss things. set a goal, say this evening, I will get the upper outboard wing sanded completely, stay at it till thats done, it will be a motivator that you are "completing" a task each time you work on it.when you get frustrated, STOP, walk away for awhile and then come back when you are fresh. It takes a LOT longer to fix screw ups than it does to simply walk away and come back later
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Hi guys,
This is interesting that you don't use heat???? I've watched video's of Windy setting his planes next to a heat vent??? In good old CA we paint in 100 degree weather??? I figured you would be better off in a controlled heat room, maybe 80 degrees???? Not doubting what ya said, just curious what would be the best condition???? Its either to hot or to cold, which is the best??? Don't ya sand after each coat of paint until the last coat of clear??? To much moisture in the air can make the paint job look bad??? Just to many things to go wrong???? Anyone that can do a great paint job has to be an artist and Mr. Randy Powell is the best in the West.
Gary
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You have plenty of time - no need to rush .
I pump out a few models a year - To Paint takes only a few days - week tops depending on how many colours.. 1 day to paint 1 day to dry 4 colours 4 days - 1 to clear - 1 to wait for clear to go off - thats 6 days.
Its the PREP - any car body place - and GOOD painter will tell you this. Its all in the prep ( mind you buffing out clear will hide SOME things just not all things )
I could if PUSHED - like randy get a model to paint from bare wood to clear in 6 - 7 days. - This would be mostly on prep and would pump the paint down to 2 days- paint in a booth - each colour drying time of 30 - 40 mins.
The key is PREP PREP PREP. - One shortcut you can use - is skip sanding the dope , spend all your time sanding the top coat with dope / talc mixture.. - Ideally you dont want to skip any steps - but ive had good finishes just giving it a token sand. then focusing on the final stage.. Use an auto sandable primer also and wet sand that - you can shave off 3 days.
I concur also with Randy - Depends on your time schedule.. I'm trying to get my Nats model finshed also -
Get home from work 6ish - eat .. out in the garage by 8pm - Work till 1:30 - 2. ( thats 5 hrs )
Do that 4 Nights a week have Tues nights off.. ( 20 Hrs a week )
On weekends - Treat it like a work day - Get out into the Shop by 8am - work till 7pm stopping for lunch and dinner ( 11 hrs )
Repeat on Sunday ( Another 11 hrs )
Thats a total of 47 Hrs in a week.. Can get close to 100 hrs in just over 2 weeks of SOLID and i mean SOLID work.
I would also do this during a season to get the model up to a building stage - then slow down - I dont enjoy pushing myself EVERY week day - But I have an old saying " I can sleep when its finished.. "
Whatever my project..