Brush vs Spray on Trim


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Old 02-20-07, 08:19 PM
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Brush vs Spray on Trim

I have a whole house worth of trim to finish. The wood is Maple and the desired finish is semi-gloss clear coat (no stain). I would like to use water based poly to minimize yellowing (learned this on a previous post, thanks...).

I was looking for a few experienced opinions...

Would it be worth setting up a "paint booth" in the basement, so I can spray the trim quickly?

I was thinking of lining the walls, floors and ceiling with plastic to minimize dust and contain overspray... and using a window fan blowing air out on oneside of the booth with air filters on intake side for ventilation.

I want to get this trim done as quick as possible but still want a reasonably good finish.

If someone thinks spraying is the way to go, can you provide a few suggestions:

- is there a special type of poly recommended for spraying
- should it be diluted
- what type of sprayer
- what surface prep do you use with water based poly (with oil based I normally wipe down with mineral spirits... but, not sure about water based)
- what type of mask or respirator is recommended?

Thanks,

Steve
 
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Old 02-21-07, 07:31 AM
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Hey Steve

Most of my experience with staining/poly new woodwork is with new home construction. I'll skip the stain part since it doesn't apply.

Using saw horses I'll spray a coat of sealer/poly on the woodwork. I often spray the woodwork outside where there is both more fresh air and I don't have to cover up or keep the floor clean - may not be a good idea if you have close neighbors or finished yard/driveway.

Generally I set up and spray as much as I can with saw horse [improvised] at 1 time. Then I'll pick a good area [covered and close by] to stack the sealed woodwork. Lay scrap wood on the floor to keep the trim clean. You also need to insert [preferably narrow] wood between the stacks of trim to prevent sticking. Repeat until all wood is sealed.

If time allows I'll sand when dry and spray on the 2nd coat. The finish coat is always applied by brush after installation - except the doors which I'll spray.

That brings us to the prehung doors. These I'll open them up [inside the home] seperate the jambs [if applies] and spray these standing up using care to not get any sealer on the ceilings. At this point, I've already primed the walls and finish coated the ceiling if applicable.

I seldom use waterbased varnish/poly and have never done a new home completely with waterbase.

I always use an airless to spray the varnish/poly. A 4-13 tip works best but you can use a smaller tip if neccessary.

Sanding and dusting should be sufficent prep. Ink marks/stamps can often be removed with denatured alchol.

Use a regular painting respirator. If they haven't jumped in price you should be able to get one with charcoal filters for $30-$40. Of course you can also get more expensive ones with complete face mask, fresh air, etc.

Hopefully I covered it all, if not just holler,

mark
 
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Old 02-21-07, 05:01 PM
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Mark,
Thanks for all the info. It looks like you talked me into spraying.

The casings that I am using are beaded with a lot of peaks and valleys.... and will be a major pain to sand. They feel and look real smooth, do you think pre-sanding is necessary, unless I come across a rough spot? Can I use steel wool between coats?

How do you dust after sanding? I have wiped down with a damp cloth of mineral spirits to remove the dust when I have used oil based in the past... any suggestions what to use for water basd poly?

Since this is a one time thing for me, do you think I can get by with an air powered sprayer? I am thinking it'll be cheaper, but don't want to put a shabby finish job on whole house full of trim.

I'll be finishing all the trim before it's hung. Do you think I can spray the last coat to save some time?

Thanks for all the advice,

Steve
 
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Old 02-21-07, 05:48 PM
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spraying poly

As mark says for a proper finish you need to scuff the first coat. The first coat on bare wood tends to raise the grain and your beautiful trim takes on an
almost furry finish. You then knock this off with sandpaper. I like to use a shop-vac with a detail brush to remove the dust. But I usually spray trim after its been installed.
For a finish that is sandable, durable, washable and beautiful you have to use solvent based clear coat.
If you decide to use an air powered gun you need a really, really big compressor. The amount of air required to blow on a decent finish is huge.
Like Mark, I too use an airless sprayer for any on site spraying.
The job will be sticky and smelly. You definetely need a respirator and cover up well. Leave no body part exposed, it will get blasted. Eye protection doesn't really work well, the shield or lense gets smoked pretty quick and then what do you do? When spraying oil I like to put Petroleum jelly in my eyelashes and smear it all around my eyebrows. When I'm finished I simply wipe it off and wash with water.
 
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Old 02-21-07, 06:13 PM
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An air powered cup or pot can spray oil base poly/varnish fine but it will be slower and have more overspray. I've never had a lot of success spraying water based coatings with a cup gun. I'm not sure if I've ever sprayed any water base varnish/poly.

I often use the little sanding sponges for sanding woodwork. They bend in the contours fine and are fairly easy on the hand. As pg stated the first coat tends to raise the grain and must be sanded, it isn't imperitive to get in every nook and cranny. The main thing is for the end result to both look and feel smooth. Sanding between coats also promotes better adhesion. While a rag damp with the appropriate thinner works best, often dusting with an old brush is sufficent.

If you use a waterbased coating DON'T use steel wool. Small particles of steel will wear/break off and wind up getting left behind - when the waterbased comes in contact = rust, ugly stains

The final coat should be applied after the trim is installed. That way all the putty also gets coated. Personally I think brushing the final coat [except doors] does a better job. Once you either protect the walls or double coat with wall paint to cover the overspray I don't know that any time is saved.
 
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Old 02-21-07, 06:18 PM
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Originally Posted by painter guy View Post
Eye protection doesn't really work well, the shield or lense gets smoked pretty quick and then what do you do?
Very true!!!

I wear glasses and when I start having trouble seeing, it is time to take them off and wash them with the appropriate thinner. My lens are made of glass so thinners won't affect them - don't try to wash plastic lens with thinner!!!
 
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Old 02-21-07, 06:23 PM
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If you decide to use water based poly, you do NOT want to use steel wool at all. Sanding the casing profile isn't a big deal... just get yourself a handfull of 3M Sandblaster sanding pads... 180 grit works well for knocking down the sealer coat, and the 320 works well inbetween the other coats. They get into the grooves well. I always prep my trim before staining by sanding with 120 grit, maybe 150 if I'm feeling frisky. I hate to see planer knife marks in my trim after it's stained.
 
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Old 02-21-07, 08:03 PM
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Thanks for all the info guys.

Originally Posted by painter guy View Post
For a finish that is sandable, durable, washable and beautiful you have to use solvent based clear coat.
Do you mean use solvent based poly on the last coat over the other water based coats?..... or ALL coats solvent based? I was planning to use water based to prevent yellowing the maple trim. I am trying to match the natural maple panelling that the trim is going over as closely as possible.

Looks like I'm off to buy an airless sprayer.... I can blame it on you guys when the wife asks why I had to have it!!

Thanks,
Steve
 
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Old 02-22-07, 06:01 AM
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If you buy a spray pump the piston pumps are more durable than the diaphram pumps - also more expensive. They can be rented.

As you know oil base varnish/poly will change the color of raw wood. If the wood is already sealed with waterbased the oil shouldn't deepen the color any but it will still amber with age. I'd stick with waterbase if that is what you start with.

I'm not real familiar with waterbase clear coatings but know that some are a lot more durable than others. Maybe top coat with a floor coating? for a tougher finish.
 
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Old 02-26-07, 08:04 PM
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I was out shopping for airless sprayers tonight... I'm not really wanting to spend too much money for one, because after I finish this trim project, I won't likely use the sprayer but once every year of so. I am a little afraid of renting... because I only want to clear coat my wood and am a little afraid of any color left by the guy who rented before me (is this somthing I should worry about?).

It looks like an entry level sprayer at one of the chain hardware stores will run around $300. I looked at several... they all appear about the same to me... are there any major watch outs?

How do you clean these things? Just suck solvent up the dip tube and blow it out the nozzle? Or is it a long process?

How long can you leave the sprayer with poly in the hose/pump? In other words, can you lay it down for 15 minutes while you swap trim in and out of you paint area? For 30 minutes while you eat dinner? , etc.

Thanks,

Steve
 
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Old 02-27-07, 04:50 AM
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I'm not familiar with the lower price units.

It is possible to pick up color from a poorly cleaned airless but running thinner thru it first will usually eliminate this problem. Basically you pump thinner [water if using latex] thru the pump until it comes out clean. When flushing with water it is always best to finish with thinner - this coats and protects the pump from rust. There are also various filters that need to be removed and cleaned. A proffessional type unit will have a strainer at the base of the pick up tube, a manifold filter at the pump and another filter in the gun.

There shouldn't be any problem leaving paint/poly in the system while you take a break or do something else. It may be benificial to remove the tip and soak it in the proper thinner. I don't know if it is an option with the home owner type pumps but a reversible tip is real handy - if a little paint dries in the tip, reversing it will usually blow the dried paint/trash out.

A new pump might come with a video and will have paper work so familiarize yourself with the operation of the unit before you start.
 
 

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