sanding prior to painting
 

I need to finish a LOT of house trim. It has been milled and sanded to 220.

I have been thinning and spraying Benjamin Moore's "Regal" undercoat and "Impervo" top coat. These are water borne and need some care in sanding.. My first thought was to raise the grain with water, sand to 320, prime it with the undercoat, sand again with 320, and finally 3 coats of the Impervo.

Since I am getting into "mass production" now, I would like to sreamline the process a bit. Since I am using water borne paint, it will raise the grain. Can I just spray the undercote, and sand to 320, and then apply the top coat?

Len

sanding prior to painting
 

"Len" wrote in message

I need to finish a LOT of house trim. It has been milled and sanded
to 220.

I have been thinning and spraying Benjamin Moore's "Regal" undercoat
and "Impervo" top coat. These are water borne and need some care in
sanding. My first thought was to raise the grain with water, sand to
320, prime it with the undercoat, sand again with 320, and finally 3
coats of the Impervo.

Since I am getting into "mass production" now, I would like to
sreamline the process a bit. Since I am using water borne paint, it will
raise the grain. Can I just spray the undercote, and sand to 320, and
then apply the top coat?

Sanding to 320 is way overkill IMO. It is already at 220 which is more than
enough for primer. I'd spray the primer, sand again - lightly - with 220
and do the top coats. If this is outside trim I wouldn't bother sanding the
primer. If it is inside trim I might sand lightly but I wouldn't be using
waterbase Impervo, I'd be using the alkyd Impervo.



--

dadiOH
____________________________

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sanding prior to painting
 

On 6/9/14, 3:32 PM, Len wrote:
I need to finish a LOT of house trim. It has been milled and sanded
to 220.

I have been thinning and spraying Benjamin Moore's "Regal" undercoat
and "Impervo" top coat. These are water borne and need some care in
sanding. My first thought was to raise the grain with water, sand
to 320, prime it with the undercoat, sand again with 320, and
finally 3 coats of the Impervo.

Since I am getting into "mass production" now, I would like to
sreamline the process a bit. Since I am using water borne paint, it
will raise the grain. Can I just spray the undercote, and sand to
320, and then apply the top coat?

Len


You may want to consider Zinsser B-I-N primer. It's pretty expensive
because it's shellac based, but it's well worth it. It'll save you on
sanding because it dries so quickly and doesn't raise the grain like
water. It also sands baby-butt smooth, so you'll likely save a top coat
or two.


--

-MIKE-

"Playing is not something I do at night, it's my function in life"
--Elvin Jones (1927-2004)
--
http://mikedrums.com

---remove "DOT" ^^^^ to reply

sanding prior to painting
 

I agree with dadiOH and haven't sanded paint finishes past 220 in years. If you are sanding correctly, you simply don't serve any purpose in doing so unless that suits your personal taste. I would say that 99% of people sand way too much anyway to make up for woodworking deficiencies, poor finishing, and for some reason it seems to make some folks feel like they are connecting to "fine woodworking" when they get to the sanding stage.

As far as sanding latex, I don't know any professionals that sand latex unless they are correcting the incidents listed above. It isn't necessary, and I have even gone weeks between coats and had no adhesion problems. Latex by nature is a porous finish and subsequent coats will adhere just fine. Stay with the same product and there won't be problems.

I like the idea of changing to alkyd finishes. If I can, I apply those.

If I have to prime, I like BIN over all other products. No thinning needed, you can put it on whisper thin, shoot it with the same tip (I use 1.2mm) that you use to shoot finish, and it doesn't foul the guns. Plus... it just works.

But Len, if you are in "production mode", why are you priming? Most of the time it adds nothing to the finish if you are starting with new moldings, trims, doors, shelving, plywood, etc. Priming is a good idea if you are painting dirty wood, over old finishes, or painting over contaminated finishes. It is also a good idea if you are painting over finishes in areas that have had a lot of cleaning such as in kitchens, baths, etc., where spray cleaners and soapy products or other chemicals might leech into your new finish.

If you are coating new materials, use the same paint you are using for finish as the primer, mid and top coats. NOTHING sticks to a finish like itself as it is specifically formulated by the manufacturer to do just that.

Put the sandpaper away, ditch the primer, and keep the Impervo. That is some really good stuff. I have only used it on one job but shot a lot of it, and it was like shooting liquid plastic. Shot clean, required little thinning in my pressure sprayer but none in my airless, and the finish tightened up to a glassy smooth finish when applied at 3 mil for the first two coats, then a bit thinner on the last.

I think in "production mode" you should load your gun and start shooting.

Robert

sanding prior to painting
 

Len wrote:
I need to finish a LOT of house trim. It has been milled and
sanded to 220.

I have been thinning and spraying Benjamin Moore's "Regal"
undercoat and "Impervo" top coat. These are water borne and need
some care in sanding. My first thought was to raise the grain with
water, sand to 320, prime it with the undercoat, sand again with
320, and finally 3 coats of the Impervo.


I would not sand to 320. Beyond 220 you run the high risk of burnishing the
wood. 150 would likely be plenty fine - especially for a paint finish.

Since I am getting into "mass production" now, I would like to
sreamline the process a bit. Since I am using water borne paint, it
will raise the grain. Can I just spray the undercote, and sand to
320, and then apply the top coat?


Read the manufacturer's directions. When all else fails - defer to that.

--

-Mike-

sanding prior to painting
 

On Monday, June 9, 2014 3:32:25 PM UTC-5, Len wrote:
I need to finish a LOT of house trim. It has been milled and sanded to 220.



I have been thinning and spraying Benjamin Moore's "Regal" undercoat and "Impervo" top coat. These are water borne and need some care in sanding. My first thought was to raise the grain with water, sand to 320, prime it with the undercoat, sand again with 320, and finally 3 coats of the Impervo.



Since I am getting into "mass production" now, I would like to sreamline the process a bit. Since I am using water borne paint, it will raise the grain. Can I just spray the undercote, and sand to 320, and then apply the top coat?



Len



I was under the impression that water borne products needed to be sanded to 320 to get a smooth final finish.

Impervo is not latex. It is an acrylic.

I found that the primer/sanding sequence sealed the wood (poplar) and gave me a smooth surface to start spraying with top coat.

I am using a 4 stage Fuji gun. In the earlier tests I found that thinning was needed. But, I can try without thinning again. I don't relish the idea of 4 coats (primer plus three top coats).

sanding prior to painting
 

"Len" wrote in message

I was under the impression that water borne products needed to be sanded
to 320 to get a smooth final finish.

Impervo is not latex. It is an acrylic.

All acrylic paints are latex; nor all latex paints are acrylic.

None of them sand worth a damn...it is like trying to sand rubber.
__________________

I found that the primer/sanding sequence sealed the wood (poplar) and
gave me a smooth surface to start spraying with top coat.

Primer helps give a smooth surface because it contains a bunch of filler,
usually/often calcium carbonate (note how heavy a can of primer is). That
filler flows into imperfections and helps smooth things generally. In days
of yore, it also made a primer that would sand easily. Them days are pretty
much gone :( with a few exceptions.

--

dadiOH
____________________________

Winters getting colder? Tired of the rat race?
Taxes out of hand? Maybe just ready for a change?
Check it out... http://www.floridaloghouse.net