I have just acquired my first real spray gun (HVLP gravity fed). I am going to practice with some shellac and then lacquer (not on the same piece). Actually, the first practice will be with water against the fence!
My question:
With very quick-drying material (10 minutes in some cases), do you have to strip the gun and clean it with solvent immediately after spraying? For example, I will put an initial coat of shellac on a wall cabinet. I will then have to sand before I can move to the next coat. So I cannot just let the gun stand. Or do you just let the gun sit in a bath of solvent?
Related question: What size tip should I use with the shellac. I have Zinser 3lb. (waxed) cut that I am going to dilute to 1lb. I have 1.3, 1.4 and 1.5 mm tips.
Would appriate some help from the experts here!
Hastings
Replies
Hastings,
I wouldn't call myself an expert, but I have sprayed quite a bit of shellac and other materials. My first suggestion is to practice on scrap with shellac or whatever you are going to spray before going to a project. Water doesn't spray like finish.
When I am spraying shellac I will let it sit in the gun if I am going to be spraying more within an hour or two. I have never had any problem with this. At the end of the day just put a little DNA in the gun swirl it around and spray it until it is gone.
Tip size is dependant on the gun itself, the viscosity of the finish, the pressure you are spraying at, lots of things. Try the medium tip with the shellac and see how it works. You shouldn't have to cut it down to a 1# cut, a 2# cut will build much faster and shouldn't be a problem to spray.
Two shellac tips: Don't apply shellac as you would other finishes, thicker isn't better with shellac. You want the thinnest finish that will give you the results you want. Try mixing your own shellac fresh from flakes. It dries quicker, it has better moisture resistance, you have a much wider choice of grades, and you don't have to wonder if it is too old and is going to get all gummy.
Rob
Rob:Thank you so much for the advice and tips.Hastings
Just run a small skoosh of the relevant thinners (solvent) through the gun either at the end of the day or between uses if the periods between use are extended-- say three or more hours. Top cup (gravity fed) guns are the easiest of all to clean. I can do a full clean of these guns at the end of the day in less than five minutes.
Even if you screw up and forget to clean the gun and it's left lying around for days on end becoming all clarted up with solid polish all is not lost. Both lacquers and shellac are easily redissolved with the appropriate solvent, ie, lacquer thinner for lacquer and alcohol for shellac. In fact lacquer thinner will also dissolve shellac although it's not the appropriate thinner for it.
For low viscosity polishes such as those you are planning to use-- laquer and shellac, your smallest needle and tip set, i.e., 1.3 mm should be appropriate. Slainte.
Richard Jones Furniture
That's just what I needed! Thank you.I am OCD enough to have cleaned the gun between coats!Do your comments about the lacquer also include catalyzed lacquers?Hastings
"Do your comments about the lacquer also include catalyzed lacquers?"
Yes, both pre-cat and post-cat lacquers will redissolve in cellulose (aka lacquer) thinners.
But Steve later made the very valid point that guns used to apply waterborne finishes need to be cleaned out almost immediately after use. Slainte.Richard Jones Furniture
Post-catalyzed lacquers are a little more fussy than the others. I would not leave P-C lacquer in my gun after I am finished spraying. P-C lacquers have a pot life and I would pay close attention to the manufacturer's recommendations. Pre-cat is a harder finish and a little more sensitive to work with than regular nitro, but it is a very good product. Much more moisture resistant and tougher finish. Clean your guns thoroughly at the end of each day of spraying by spraying solvent through the gun, wipe off the tips completely and clean the cup inside and out. I then leave some clean solvent in the cup(2 oz.) to spray out before the next days work. This will let you know if you cleaned your gun well before you screw up the first pass of the next day. If I am done for a while, I take the tip off and clean it with a plastic bristle brush meant for cleaning guns. Clean the outside of the gun as well it makes your tool look better. I have a 5 year old Sata RP and it still looks and sprays like new.
Terry
Terry,
Which SATA RP gun do you have? I just got this http://www.spraygunworld.com/products/SATA/SATA%20SAT87908-1.htm one, and I love it. A big step up from the $65 dollar gun I had. Spray Gun World also has great prices. The KLC-RP I got was $25 less than even Amazon has it for. They also have a wealth of info on their website including a section just for us woodworkers.
Rob
SataJet Digital 2 RP gun and I really like it. I don't pay any attention to the digital readout because I go by feel and performance, but it still a finely engineered tool. I have been advising people on the forum every since I have been a member to use spraygunworld. Their customer service and advice on guns and tips is the best. I don't get as good advice at my local Sata dealer. They knew nothing about spraying furniture lacquer. I went from a Binks so the jump was not as much, but still a big improvement.
Terry,
Satajet Digital huh? You really went all out. I bet it is nice. Mine is like half the price and I am very impressed with how precise and adjustable it is.
Spraygunworld is great. I like to gather as much info as possible before asking questions or making a purchase and their website certainly allows that. I bet I spent 4 hours on it narrowing down my options. They really put a lot of time into their site and they are super helpful. All that and the best prices you will find on value priced guns to the top of the line stuff like yours.
Rob
Rob,
I cannot take any of the credit for making a very wise decision on which gun to buy. One of my best friends owns a body shop and teaches autobody repair at a local Vo-Tech HS and he told me I would like that gun the best after using the Binks for so many years. He was right, it is an amazing tool and spraygunworld was the place to buy it. When I bought my gun they had a woodworkers special ($350) on that gun and I got it cheaper through them then my buddy could get it wholesale.
Terry
Edited 4/15/2007 3:49 pm ET by terrylee86
How wide is the fan with that one? I've got a SATAJET 90-2RP gravity gun and I must say that I'm very dissatisfied with the fan width which is about 5 to 6 inches at it's widest. The other thing I don't like about it is that it takes quite a bit more atomizing air than an HVLP to even the fan out. Other than that it's a fine, very well made gun, but honestly is not even close to my DeVilbiss GTI's performance in any respect. Paid $320 brand new for it about three years ago on a close-out special. The GTI is close to 10 years old (bought it used) and sprays circles around the SATA. It's really not even close.
I would say the fan is 6-8"the way I have it adjusted and I get great atomization, but I have never used a Devillbis gun so I have no frame of reference. I went from a Binks Model 7 conventional siphon gun and my Sata does a much better job without the cloud that use to envelop me. I wonder if your tip is not big enough. I bought the woodworkers combo and got a 1.6 tip I think the biggest they sell for your gun might be 1.4. I would call the guys at Spraygunworld and ask.
The aircap is what controls the fan width more than the tip does. I've heard good things about sprayworld.com, but I buy from a buddy that chalked up many years as a finisher and a painter before going into sales. In fact he was my direct supervisor at the last place I worked. He tells me that the Jet 90-2RP is known for not having a very wide fan. Which may be part of why SATA discontinued it.
Just to emphasize this point--shellac and lacquer redissolve in the solvent, but waterborne and catalyzed finishes don't. The latter need to be cleaned before they cure. Otherwise it is a dismantle and thoroughly clean the gun.
I have left Shellac in the gun over night, I just make sure the paint siphon tube is full so it can't dry. Shellac is corosive to Aluminum so it is probably best to not leave it in the pot more than a few hours. I have left Nitro Lacquer in the gun for a few hours as well, again makeing sure that the siphon tube is full of finish. Any catalysed finish needs to be removed and cleaned imediately. Aside for the obvious problem of the finish hardening, most of the catalysts are acids the will eat up aluminum parts.
Pardon my spelling,
Mike
Make sure that your next project is beyond your skill and requires tools you don't have. You won't regret it.
Mike:Thank you for your advice. I bought those handy pot liners; one less thing to clean up!Hastings
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