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spraying epoxy finish, choice in gun?

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spraying epoxy finish, choice in gun?

Postby TargetSlayer » Thu Dec 19, 2013 11:58 am

Now that I'm getting adequate performance on one bow and great on another (much thanks to your help) I'm ready to move from polyurethane aerosol finishes to epoxy. I have a little consumer air compressor that's a step up from the lowest ones, so for someone who can't invest in much right now, I'm thinking, do I buy:
1) a "low-pressure, low volume model"? Or maybe even airbrush since it's one bow at a time (maybe two lined up but sprayed individually)

2) top/gravity feed or siphon? I thought I'd have more movement control with siphon but for small quantities maybe gravity leaves less excess and/or can be moved around more without bowing air when level is low?

I'd think if the pattern would spray wide enough an airbrush kit would allow you to make and use small quantities for the multiple sprayings? Wouldn't some 32 or even 20 oz. "low volume" thing maybe still require far more CFM than required, wasting 100's of % in epoxy?
No?
Thank you in advance and, as usual, I sincerely value ya'll's replies, posts, blogs, books, articles, and in some cases products, more than I can say.
-Jeff
I was planning on (until maybe I sell a bow and order T-Bird) using my DER 383 + Versamid 140 thinned like 10:1?
I got that since I saw someone spray it, and I'm trying my first bow construction with it as a Smooth-On alternative for lamination esp. in cooler weather and maybe less gooey waste...hopefully it holds and flexes as well as smooth-on because this one coming off the form is a horsebow that concetrates work in smaller places (not intended to have quite the longevity of one of my standard reflex deflexes that might last 2 generations of people)...would be nice still to spray all my bows with epoxy finish.
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Re: spraying epoxy finish, choice in gun?

Postby Kenro » Fri Dec 20, 2013 7:59 am

Epoxy is going to be different but not all THAT different that you will need to get set up with anything more than you will spray anything else with.
I suggest for what you are doing to not buy siphon feed.... gravity feed is the way to go.

For the amount of bows that you are doing and if you are on a tighter budget, You can get by just fine with the cheaper hvlp gravity gun from harbor freight.(about $20.00) They make slightly better quality automotive touch up guns ($40.00 range)from bumper to bumper that are a little better in quality and if set up right can really lay down a nice finish if you take your time. If you really want to get serious and want the forgiveness to not be so perfect in technique then you will be getting into the $150.00+ range for a gun! These guns cost more for a reason!.. However......NOT NEEDED.
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Re: spraying epoxy finish, choice in gun?

Postby TargetSlayer » Fri Dec 20, 2013 8:18 am

Thanks as usual K, now you said hv, lp... I guess low volume mightn't finely atomize the spray finely enough?
Remember if anyone's coming in at this point I'm only aiming at one bow at a time.
Also, I prefer a thinner solution, I'd rather spray more times with thinner mix and I really get off on cutting most of the viscosity out with a low epoxy ratio (higher in solvent) by nature. We're discussing what guns I can get on a budget. The $40 above sounds good for now; I'm actually going to HF right now with my family reunion...
thanks again
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Re: spraying epoxy finish, choice in gun?

Postby BK in TEXAS » Fri Dec 20, 2013 8:36 am

Like Rolo said....the $25 purple Harbor Freight gun works great. I've run a couple gallons of Krystal finish for bows through it, and many many gallons more of paint through it refinishing furniture and other stuff. If this ever wears out I'd happily buy another.
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Re: spraying epoxy finish, choice in gun?

Postby Kenro » Fri Dec 20, 2013 6:17 pm

TargetSlayer wrote: Also, I prefer a thinner solution, I'd rather spray more times with thinner mix and I really get off on cutting most of the viscosity out with a low epoxy ratio (higher in solvent) by nature.



You only have to thin the flat or satin sheen epoxy to get it thru the gun if you choose to use it. I never thin the gloss. Otherwise its real easy to run. Besides that.....the more thinner you use the more the surface shrinks from solvent evaporation.
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Re: spraying epoxy finish, choice in gun?

Postby Kirkll » Fri Dec 20, 2013 7:40 pm

There's a disadvantage to spraying too thin while using epoxy . If you sand through the layers of finish, especially if you sand into the wood, you'll see the overlay lines in the finish. there is a lot to be said for laying down a couple wet coats with the thickest viscosity your gun will atomize, so you are just sanding your material flush between coats. if you use your tack time just right you can get a good build up laying down pretty flat without sanding between coats too..... it just takes some time learning your material....

That Purple HVLP gun at harbor freight will do you fine, just make sure you've got 03 or an 04 tip. I've wore out a couple of them now, and just jumped up to a pro gun not long ago. The only reason i did that is so i can get a little finer adjustment and i can buy parts for this one and different sized tips. Once you get to where you are spraying a lot, i think its worth going to the pro gun.
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Re: spraying epoxy finish, choice in gun?

Postby TargetSlayer » Sat Dec 21, 2013 9:13 pm

If I'm starting out with DER 383/ Versamid epoxy because I'm already using it for lam and I saw a really nice bow finished with that and acetone, does anybody here use it and how much do you thin that (ratio?)
It's not as thick as smooth-on but it pours with syrup viscosity...
If in doubt I guess I'll experiment with the gun I got and go thick per your new info. guys THANKS...

I might have gotten the purple gun since 2 of you said that, but I was down there prior to replies and got
the "$49.99 on sale for $34.99" hvlp "touch up" one...
http://www.harborfreight.com/hvlp-detail-spray-gun-46719.html
It's got the conveniently smaller cup, 3.2 to 5.6 CFM @ 43psi
pattern 110 to 160cm
Since I'm aiming at one bow at a time I figured less overspray (waste) than some and I only have a 2.5 gal. air tank with a 5 gal. extend-o-tank bringing it up to 7.5 gal air tank cap (only 1/2 gal. over minimum recommended... then again I don't know if it will be 3.2 CFM or 5.6 CFM when I like the spray). I see how to do the math on that but sometimes hands on introduces new variables, but in any case the lower CFM was attractive since I don't have a pro air compressor.

Thanks for the comment on the tack time vs. sanding...
What I've been doing with polyurethane is hand-brushing or rubbing the bare wood on the riser and thin limb sides for 2 or 3 coats sanding in between lightly, then spray poly everything including black glass afterward 3 coats with zero sanding... I'd heard there was something better about spraying a second coat while tacky (instead of dry) but when I've gotten detained elsewhere, spraying polyurethane over dry polyurethane (still with no sand) I haven't noticed a difference even on the black glass showing every flaw... maybe it won't hold up the same after extended use I dunno...I will be prepared for timing to be more crucial with epoxy. But if I understand correctly, you let epoxy tack over some and spray again if you don't want to sand (esp. last coats)?
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Re: spraying epoxy finish, choice in gun?

Postby TargetSlayer » Wed Dec 25, 2013 1:10 am

Thank You All
and to All a Good Night!
MERRY CHRISTMAS!!!
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Re: spraying epoxy finish, choice in gun?

Postby Kirkll » Sat Dec 28, 2013 10:49 pm

well i hate to break it to you bro.... but you got the wrong gun there with a .8mm tip.... you need a 1.3 or a 1.4 mm tip for clear coating.... you could use latex paint through an .8 tip. That is huge. they typically use that for auto primer. you'll be shooting way too much material trying to squirt clear..

harbor freight has a kit that has two guns in it. one is a touch up gun with a 1.0 tip too small for spraying bows IMO, but can be used with real thin material for touch up. the second gun has two tips included. a 1.8 mm and a 1.4 mm that's the gun you want. put the .4 tip in it.

http://www.harborfreight.com/profession ... 94572.html
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Re: spraying epoxy finish, choice in gun?

Postby TargetSlayer » Mon Dec 30, 2013 3:30 pm

Kirkll wrote:well i hate to break it to you bro.... but you got the wrong gun there with a .8mm tip.... you need a 1.3 or a 1.4 mm tip for clear coating.... you could use latex paint through an .8 tip. That is huge. they typically use that for auto primer. you'll be shooting way too much material trying to squirt clear..

harbor freight has a kit that has two guns in it. one is a touch up gun with a 1.0 tip too small for spraying bows IMO, but can be used with real thin material for touch up. the second gun has two tips included. a 1.8 mm and a 1.4 mm that's the gun you want. put the .4 tip in it.

http://www.harborfreight.com/profession ... 94572.html



OK well THANK YOU so much I'll return it for one or both of the others,

but you have me confused:

at saying 0.8mm is huge and will spray too much in relation to a 1.4... the manual for this .8mm gun says do not attempt to use latex...
0.8mm is smaller than 1.3mm or 1.4mm, not larger... did you mean to say .8mm will be too small, restrictive, maybe I'd have to thin it too much etc.? Thanks for sharing your sizes that work best either way!

Kinda sucks, I like this little gun, seems a little nicer than the purple one half the price. I guess I was going for a bit fewer CFM since mthis year's bows are all going to be 1 in. wide and around 50in. long, really small Asiatic recurves (pics up next. But if .8mm is too small period I'm hosed so to speak.

I am going over black glass on top (the whole reason I started spraying aerosol, I can't hand-do over black glass and not look retarded). I like the fine matte grain of light coats of full-pressure can aerosol poly-u over that black glass but I want the strength of epoxy.

I'm still thinking this is the $40 automotice touch-up one Ken said he felt would, "...lay down a really nice finish if you take your time"? but it's Central pneumatic not "bumper to bumper"...

I'll still probably take it back unless Ken says he used this one, because I now have like three statements the purple ones work... and while my first guy said thin 10-to-1 thinner/epoxy, you veterans have spoken about thicker coats and I trust you folks; I can't afford to waste money time or weird layers visible going too thin I suppose! I still hand-seal exposed wood a couple times first with a fine brush back and forth, like rubbing in with cloth but I prefer small brush along wood grain, before spray anything.
(HF is just a long drive LOL)
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