LumberJocks

Guessing how much poly is needed to be used upon a project before hand

  • Advertise with us

« back to Finishing forum

Forum topic by Holbs posted 05-26-2017 03:59 PM 1174 views 0 times favorited 7 replies Add to Favorites Watch
View Holbs's profile

Holbs

1723 posts in 1867 days


05-26-2017 03:59 PM

Topic tags/keywords: poly finishing hvlp

I am spraying a project for the first time using my Summit HVLP system. I’m happy with it (for a beginner). I have so far sprayed 2 coats upon roughly 4 window jamb pieces of 5’x4” knotty alder boards. I’m nearly 1/2 out of my quart. Unsure if I am using “too” much or if this is about right for the amount. This leads to future project questions. Is there a rule of thumb in regards to how much medium (poly, varnish, etc) to have on hand prior to starting a project? Something like a quart for so many board feet? I may toss on a 3rd coat depending on what I see from my 2nd coat later tonight. Can already tell, will need another quart for the casings.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter


7 replies so far

View Rich's profile (online now)

Rich

1982 posts in 427 days


#1 posted 05-26-2017 04:27 PM

That’s the sort of thing I keep notes on as I work, so that I can use that information to plan in the future. You’ll also simply develop a gut feel as you gain experience with your sprayer. The sq-ft per gallon, or whatever, on the can is for brushing — and even it is an approximation based on typical application. You have different variables with your sprayer, such as what flow rate you’ve set, overspray, etc. Overspray is really the key, because that’s finish that’s being used up, but not getting on your surface. I’m not sure if anyone can give you a definitive answer because of those.

Edit: I always buy more than I need. Gallon cans are more economical per ounce than smaller quantities. To keep it from going bad, I keep those cheap empty paint cans you can get for a couple of bucks around, and divide up the gallon into four quart-size ones of those. Label them, and you’re all set. It will save money, and the cans are re-usable.

-- No matter how much you push the envelope, it'll still be stationery.

View pintodeluxe's profile

pintodeluxe

5466 posts in 2651 days


#2 posted 05-26-2017 05:03 PM

About twice what you think you need.

I spray lacquer more often than anything else, but I notice the second coat doesn’t eat up as much finish as the first.

I used to buy in 5 gallon quantity, but now just get gallons.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View AandCstyle's profile

AandCstyle

2905 posts in 2095 days


#3 posted 05-26-2017 09:40 PM

Holbs, another consideration is the shape of the pieces you are spraying. Less product per square foot is required for large pieces than for small ones because there is much less waste. Your current project will need more finish than the same square feet if you were finishing a cabinet, for example. I agree with the others that gallons are the best way to buy finish balancing price and usage.

-- Art

View hotbyte's profile

hotbyte

989 posts in 2813 days


#4 posted 05-26-2017 09:57 PM

I always seem to need 3 more oz than I have on hand ;-)

View Holbs's profile

Holbs

1723 posts in 1867 days


#5 posted 05-26-2017 10:17 PM

OK…gallons it is. Especially considering the future plantation shutters & casing projects I have coming down the road. 5 gallons, maybe :)

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

View Holbs's profile

Holbs

1723 posts in 1867 days


#6 posted 05-27-2017 12:17 AM

For those new to HVLP and poly and finishing… that is where I am right now. I’ll admit, I did not even read the instructions on the side of my quart can:) It does not state an estimate of coverage on the label, however the website of the manufacturer clearly states a single quart can do 125 sq ft coverage. If my wood working mathematical Deep Blue computations are right, I am working on roughly 80 sq ft of space (4”x60”x4 / 12 = 80) using a HVLP which does have overspray..and I have 1 more coat to put down. I would guesstimate, I’ll have 15-20% left over in the can.

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

View Rich's profile (online now)

Rich

1982 posts in 427 days


#7 posted 05-27-2017 01:17 AM

Take the integral and perform a Laplace transform, then run it through a Dirac delta function, and you’ll have your answer. BTW, the answer is always 42.

Back to reality, the main thing with gallons, etc, is that air space in the can will oxidize the finish, so that’s why I said to pour a gallon into quart cans. The fully filled quart cans will keep as long as the shelf life of the gallon.

-- No matter how much you push the envelope, it'll still be stationery.

Have your say...

You must be signed in to reply.

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics

HomeRefurbers.com