Spray finishing advice

[Mike Kees]

Looking to start spraying finishes for cabinets and furniture. I have no experience with spraying at all. Looking for advice on how to start and what type of laquer is good to get my feet wet,so to speak. Is it necessary to have a spray booth set up for water borne finishes ? Also ,I remember seeing a book on spray finishing somewhere,does anyone have a good recommendation ?

[Jacques Gagnon]

Mike:

During my kitchen building project I bought an HVLP system Powered by a turbine. It is a 4-stage unit and has worked well for the water-borne finish I used.

My « spray booth » was fairly rudimentary but did the job of limiting the dispersion of the overspray. As your your shop is much larger than mine (single car garage) you should not have difficulty in rigging something that could fold out of the way when not needed.

I am a hobbyist; your needs may differ.

Regards,

J.

[Jim Becker]

For spraying water borne finishes you do not need a "spray booth" like you would for solvent based products, but you still need good ventilation, preferably with a way to catch the fines that will get into the air during the spray process from overspray and also still need to wear a proper respirator and vision protection. Frankly, I have an area of my shop that I use for spraying that's pretty informal and I only use water borne finishes...and sometimes a little shellac when I can have the doors open.

For spray equipment, you don't need a hugely expensive setup, but having a decent HPLV gun that handles the viscosity of the finishes you intend to use and an appropriate air source is necessary. If you have a decent, larger compressor in your shop now, an HPLV conversion gun will do the job. If you're starting from scratch, a turbine based system can take care of the need, but best results come with better units. Turbine systems have 2, 3, 4 or 5 stages. The larger the number, the more capable the system (in general) and also the higher the cost. There have been many, many discussions here on equipment.

While I originally started spraying with a Wagner HPLV Conversion Gun, I switched to a new gun from Homestead Finishing this past year that also has the 3M disposable cup setup...which not only is nice for cleanup (although I re-used the liners), but also for being able to spray at any angle with a lot of gun adjustability. I put out about $385 for that gun setup, but it's already paid for itself more than once with quality results.

[Mike Kees]

Jim thanks for the reply ,and moving my post to the appropriate forum. Does "conversion gun" mean a gravity feed gun that connects to a standard air hose ? What brand-types of water borne finishes do you use ? I have a decent shop compressor ,60 gallon Ingersol Rand already set up with a regulator and water filter in-line. How did you figure out technique ?

[Prashun Patel]

My advice is to buy a good spray finishing hvlp. Don't buy a starter system. You'll only get better and better at it and demand more and more out of the system.

I spray in my garage with a fan (and wear an organic respirator). I spray waterbased finishes and shellac. I have luck with Enduro products (clear poly and endurovar). They are forgiving, which means you don't have to dial in the pressure and pattern perfectly to make them work pretty well. Also, waterbased finishes make cleaning up easier than solvent-based.

[Edward Dyas]

Unless you are finishing light colored wood I would use a solvent based nitrocellulose lacquer. If you use a sanding sealer it's going to build fast and be very easy to work with. In warm weather you can put a coat or two of sealer on and two coats of lacquer and you are done. From start to finish only a couple hours. With a waterboarne lacquer the finish is going to raise the grain and it builds slow. What you might be able to do with 3 or 4 coats of solvent lacquer could take a dozen coats with waterborne with a lot of sanding between coats. Now the reason I say it's not good for light colored wood is a nitrocellulose lacquer is made by dissolving cotton in nitric acid and just like a cotton tee shirt the finish will yellow over time. On light colored wood you could use a type called cab acrylic lacquer, sometimes called butyrate lacquer. Another option is precatalyzed lacquer. With it you would use a vinyl sealer instead of sanding sealer which would yellow.

Actually you would need a spray booth more for a waterborne finish than a solvent lacquer. With a solvent lacquer it dries so fast the overspray settles like dust where the overspray from a waterborne finish will stick.

Spraying a finish is a matter of practice. You keep the gun about 10" from the work and spray a row of finish on and then aim at where the row terminates for the next row so the finish overlaps the previous row. visually think of it like laying roofing shingles. Each row should melt into the previoius row so when you reach the end it's a continuous sheet of finish. Just getting started you are likely to have spots where you advanced too far or went too slow where it shows in the finish. When it's dry just scuff sand it and put another coat on.

[Jim Becker]

Unless you are finishing light colored wood I would use a solvent based nitrocellulose lacquer.

I will disagree purely on a safety basis. Spraying solvent based lacquer really requires the proper setup to do it safely, at least indoors, both for health reasons and because of the extreme flammability.

Does "conversion gun" mean a gravity feed gun that connects to a standard air hose ? What brand-types of water borne finishes do you use ? I have a decent shop compressor ,60 gallon Ingersol Rand already set up with a regulator and water filter in-line. How did you figure out technique

Standard hose/air supply yes; gravity feed sometimes, cup type otherwise. Stay away from "bleeder" type guns. I personally don't favor gravity feed guns myself, especially for water borne finishes. The new gun I bought and mentioned previously will spray almost anything because of the way the pressure assist works with the disposable liner...kinda like the old Platex baby bottles with a liner that collapse as material is vacated, but with the spray gun, the pressure in behind the liner in the cup pushes just the right amount of material out to get a great pattern when adjusted correctly.

[Edward Dyas]

A solvent lacquer you can open all the doors and windows to spray it even if it's below freezing. As long as you don't let the concentration of lacquer build in the air there shouldn't be a safety issue. As far as health reasons spraying it a person should wear a chemical respirator spraying either finish.

[John TenEyck]

I often spray a coat of Sealcoat shellac then 2 or 3 coats of waterborne finish. The shellac prevents grain raise and 2 or 3 coats of WB gives a beautiful finish. I use mostly GF'S products but have used several others, too. Never have I had to spray more than 3 coats at 3 to 5 mils. What I described above can be done in one day, safely.

John

[Mike Kees]

Thanks for all the replies. I have a lot to figure out. My situation is more complicated because of fire regulations and code. My shop is a business and I am in Alberta so have to figure legal end of things as well as insurance. Do you guys have some sort of spray booths set up ? Was just checking out those online and looking at approximate costs etc. If I am required to have a spray booth it will have to be a CSA compliant set up.

[Jim Becker]

You may need a spray booth if you are commercial and especially if you have any employees or subcontractors that work with you regularly or from time to time. To what degree you need to go with that may revolved around what kind of finishes you use, too. If you spray solvent based products, it kicks things up a notch for safety, but some jurisdictions don't differentiate and make the top level a requirement even for water borne only operations. You'll have to continued your research and probably talk with the right people to get the "real" requirements you fall under.

[Edward Dyas]

Thanks for all the replies. I have a lot to figure out. My situation is more complicated because of fire regulations and code. My shop is a business and I am in Alberta so have to figure legal end of things as well as insurance. Do you guys have some sort of spray booths set up ? Was just checking out those online and looking at approximate costs etc. If I am required to have a spray booth it will have to be a CSA compliant set up.

You might keep an eye out for a used paint booth. It's not very practical to jury rig a spray booth. You see all over the internet people building a spray booth with a window fan. This is worse than a bad idea. Not only does the motor accumulate paint on the inside of the motor the motor itself can provide the spark to ignite it. An actual spray booth blower has a sealed explosion proof motor. The fans have gotten frightfully expensive over the years. I bought two about 30 years ago that weren't that much more expensive than shop fans for comfort. Now the last time I saw one they were running $800.00.

Until you can acquire a spray booth you might do your finishing work in the evenings and weekends when the fire department isn't making their rounds. You could provide ventilation by placing a fan upwind from the paint blowing clean air into the building. As long as you don't accumulate a thick cloud it's very unlikely you will have any problems. It takes a certain concentration before it's a problem. Just keep in mind that power tools can create a spark and turn the lights on and leave them on until the air clears. A light switch is enough to ignite fumes. I often go into a customers house and refinish their cabinets inside the house. I turn off anything in the house with a pilot light and turn on all the lights and put tape over the switch to prevent someone from turning them off until the fumes clear. Then I open up doors and windows needed to provide airflow through the house and I put a portable spray booth fan at the door closest to the kitchen drawing the fumes out.

[Jim Becker]

Edward, commercial operations most often cannot "roll their own" spray booth because they are regulated and inspected. It's one reason they are so expensive and why many of the makers local to me subcontract their finishing...they cannot afford to do that work in-house.

[Sean Nagle]

Unless you are finishing light colored wood I would use a solvent based nitrocellulose lacquer. If you use a sanding sealer it's going to build fast and be very easy to work with.

Edward, would you mind sharing which brand and formula nitrocellulose lacquer and sanding sealer you use? I have only purchased from Sherwin Williams, but what my local store carries seems limited.

[Edward Dyas]

Edward, commercial operations most often cannot "roll their own" spray booth because they are regulated and inspected. It's one reason they are so expensive and why many of the makers local to me subcontract their finishing...they cannot afford to do that work in-house.

That wasn't what I was proposing though. Often you can find an auto body shop that has gone out of business and selling their spray booth with their equipment or a new tenant of a building that doesn't paint anything.