Sanding Sag from BM Super Spec P22

[bmarler]

It has been a couple weeks since I repainted the area, and I believe that I may have over-reduced the paint in an attempt to get the paint through the 1.0mm fluid tip. I noticed that the paint in the areas that I touched up is showing less gloss.

For reference I reduced with 20% mineral spirits (viscosity was 22s from a #4 ford cup).

I am thinking about reshooting these areas, and reducing only by 10%. (viscosity was 52s from a #4 ford cup at this reduction). Do you have a fluid nozzle recommendation? From my research, it looks like I should try a 1.8mm.

Also, given that the paint has had a couple weeks to dry, do you think I could recoat using a catalyst enamel hardener after lightly sanding or would this be a recipe for wrinkling?

Thank you for the help.

at this point i'd be hesitant to add hardener. i'd also go with the least amount of thinner required to get a smooth finish. 5-10% maybe, preferably 5%. i usually use a 1.4 nozzle for enamel, and bring up the pressure so it atomizes well. again, i haven't used that exact paint so i couldn't say for sure. a 1.8 will probably be ok too, but will put it on pretty heavy. i'd try to keep the coats thin so they dry faster and have less chance of wrinkling. why don't you mix a small test batch up and spray a test panel so you can get your spray parameters dialed in so you don't keep adding over what you have till you're happy.

i just took a minute to look up the gun you're using. no wonder you need to reduce so heavily to get it to atomize. i'm sure it's a great gun for certain things, but i'd probably opt for something different.
i don't know, maybe you're comfortable with it, but it almost seems like an air brush to me. am i wrong?

[Patrick_]

at this point i'd be hesitant to add hardener. i'd also go with the least amount of thinner required to get a smooth finish. 5-10% maybe, preferably 5%. i usually use a 1.4 nozzle for enamel, and bring up the pressure so it atomizes well. again, i haven't used that exact paint so i couldn't say for sure. a 1.8 will probably be ok too, but will put it on pretty heavy. i'd try to keep the coats thin so they dry faster and have less chance of wrinkling. why don't you mix a small test batch up and spray a test panel so you can get your spray parameters dialed in so you don't keep adding over what you have till you're happy.

i just took a minute to look up the gun you're using. no wonder you need to reduce so heavily to get it to atomize. i'm sure it's a great gun for certain things, but i'd probably opt for something different.
i don't know, maybe you're comfortable with it, but it almost seems like an air brush to me. am i wrong?

I will stay away from the hardener, and will reduce it at max to 10%. I'll start with 5% and go up from there. Also, I'll give the 1.4mm nozzle a try and see if I can get it to lay flat. You are correct about the gun. I was using it because of its small size to get into the nooks and crannies, however I was having a lot of difficulty getting enough paint through it. I that I had it licked by reducing the paint further. It looked great when wet, but after it dried the lack of gloss was very apparent. Essentially I was forcing the paint to work with the gun, and it turned out to be the wrong approach.

I picked up on of those 3M Performance Spray guns, so I can easily play around with the nozzle size. The kit came with everything from 1.2 up to 2.0. Also, I am going to try and find a piece of scrap I can play with.

[bmarler]

I will stay away from the hardener, and will reduce it at max to 10%. I'll start with 5% and go up from there. Also, I'll give the 1.4mm nozzle a try and see if I can get it to lay flat. You are correct about the gun. I was using it because of its small size to get into the nooks and crannies, however I was having a lot of difficulty getting enough paint through it. I that I had it licked by reducing the paint further. It looked great when wet, but after it dried the lack of gloss was very apparent. Essentially I was forcing the paint to work with the gun, and it turned out to be the wrong approach.

I picked up on of those 3M Performance Spray guns, so I can easily play around with the nozzle size. The kit came with everything from 1.2 up to 2.0. Also, I am going to try and find a piece of scrap I can play with.

i've not used that gun, but it gets good reviews. looks like it runs at lower pressure than most that i've used. don't be afraid to play with that pressure setting to get the paint to lay out how you want.
i see the tips are disposable, but can you clean and re-use if you want?

did the rest of the machine you're painting have the same die back problem, or just the area you re-shot? i'm just wondering if it's a characteristic of that particular paint. lots of equipment enamels are designed to have lower gloss than auto paint would.

[Patrick_]

i've not used that gun, but it gets good reviews. looks like it runs at lower pressure than most that i've used. don't be afraid to play with that pressure setting to get the paint to lay out how you want.
i see the tips are disposable, but can you clean and re-use if you want?

did the rest of the machine you're painting have the same die back problem, or just the area you re-shot? i'm just wondering if it's a characteristic of that particular paint. lots of equipment enamels are designed to have lower gloss than auto paint would.

I was noticing the reduced pressure as well (15-20 psi vs 25-30psi). Thanks for the tip. That is correct, the tips are disposable however they appear to be easy to clean if you want to reuse them. I noticed dieback just on the areas where I reduced to 20%. The paint definitely laid down nicer however. I believe with the 10% reduction areas, I didn't get enough paint on the work due to the gun I was using combined with my limited experience.

[fj5gtx]

It has been a couple weeks since I repainted the area, and I believe that I may have over-reduced the paint in an attempt to get the paint through the 1.0mm fluid tip. I noticed that the paint in the areas that I touched up is showing less gloss.

For reference I reduced with 20% mineral spirits (viscosity was 22s from a #4 ford cup).

I am thinking about reshooting these areas, and reducing only by 10%. (viscosity was 52s from a #4 ford cup at this reduction). Do you have a fluid nozzle recommendation? From my research, it looks like I should try a 1.8mm.

Also, given that the paint has had a couple weeks to dry, do you think I could recoat using a catalyst enamel hardener after lightly sanding or would this be a recipe for wrinkling?

Thank you for the help.

I just looked at the tech sheet for P2, printed in bold letters "DO NOT THIN", clean up is mineral spirits. They also only recommend airless sprayers,fluid Pressure: 1,500 — 3,000 PSI; Tip: .011 — .015 Orifice.

I've sprayed a fair amount of enamel on machinery and steel home doors. For that stuff I just use an old cheap sata knockoff gun (probably 1.3 or 1.4 tip) and VERY little thinner, just enough to get it to spray. I don't like to use enamel, since it takes so long to before it can be handled and its always a little soft. But it is economical and keeps the rust away.

Below is picture of my 80 gallon compressor tank after I rebuilt it and put a new pump on it. That is rustoleum smoke grey (from a quart can) with an enamel hardener (whatever tractor supply was selling) and sprayed with that knockoff gun. Painted that about 10 years ago, still looks the same today, minus some oil staining and small scrapes.

https://media.benjaminmoore.com/WebS...20US%20OKF.pdf

[Patrick_]

I just looked at the tech sheet for P2, printed in bold letters "DO NOT THIN", clean up is mineral spirits. They also only recommend airless sprayers,fluid Pressure: 1,500 — 3,000 PSI; Tip: .011 — .015 Orifice.

I've sprayed a fair amount of enamel on machinery and steel home doors. For that stuff I just use an old cheap sata knockoff gun (probably 1.3 or 1.4 tip) and VERY little thinner, just enough to get it to spray. I don't like to use enamel, since it takes so long to before it can be handled and its always a little soft. But it is economical and keeps the rust away.

Below is picture of my 80 gallon compressor tank after I rebuilt it and put a new pump on it. That is rustoleum smoke grey (from a quart can) with an enamel hardener (whatever tractor supply was selling) and sprayed with that knockoff gun. Painted that about 10 years ago, still looks the same today, minus some oil staining and small scrapes.

https://media.benjaminmoore.com/WebS...20US%20OKF.pdf

Yep, I checked the TDS before thinning and called their tech support and the local commercial shop. They recommended thinning to 10% and said that they had people that were thinning it to 50%. I thought 20% would be okay. It actually laid down really nicely for the gun I was using (bad choice) but the gloss was lower in the areas I reshot.

In the end, I will switch to a larger nozzle and runs some tests with the new setup. Definitely much of the trouble was self-inflicted.

The compressor looks great! If I was to start over I probably would have used rustoleum with hardener. I was hoping I could use hardener moving forward for the reasons you stated, but sounds like I am asking for trouble so I will refrain.

[fj5gtx]

I'm surprised the tech line people deviated from the tech sheet. Typically enamel tech say thinning results in low shine and less durable end product.

Looked up my notes on enamel for indoor kept machinery, it's been a while. I use naptha for thinning (flashes a little faster), and valspar enamel hardener.

I always use primer over any bare metal. Rust-Oleum rusty metal primer over sandblasted previously rusted areas.

I tend to use more expensive products if the project lives outdoors.

Good luck !

[bmarler]

I'm surprised the tech line people deviated from the tech sheet. Typically enamel tech say thinning results in low shine and less durable end product.

Looked up my notes on enamel for indoor kept machinery, it's been a while. I use naptha for thinning (flashes a little faster), and valspar enamel hardener.

I always use primer over any bare metal. Rust-Oleum rusty metal primer over sandblasted previously rusted areas.

I tend to use more expensive products if the project lives outdoors.

Good luck !

i find the tech people will deviate from the tds more often than not. they know their product and what to expect in the field. i find with enamel (and modified enamel), faster thinners dull the finish more. i don't typically use naptha though, maybe i'll give it a shot. i get lacquer thinner and xylene in 5 gallon cans, usually i'll use one of those. the OP is in an area where thinners are more tightly regulated. here, i can get whatever i want.
i'm with you on the rusty metal primer, that stuff is the bomb. i just wish it came in more colors than just brown.

[Phil V]

It has been my experience that using more reducer is directly proportional to die back.

More reducer = more dieback.

[bmarler]

It has been my experience that using more reducer is directly proportional to die back.

More reducer = more dieback.

i'd agree with that. there's definitely a point of diminishing return if you keep adding thinner.

[Patrick_]

B Marler,

Thank you so much for the advice. I picked up a cheap piece of sheet metal, primed it, and sprayed it with a 1.4mm tip. I had to reduce it to 10%, but the key was upping the pressure to ~30psi as you recommended. I was able to get much better atomization at the higher pressure.

Now, the only question I have is that I am trying to sand the old finish, but it keeps loading my paper after only a couple swipes. There was some orange peel in the original areas. I noticed that scotch brite (maroon) on a soft block will sand nicely without clogging, but the question is whether it will remove the peel? Do you have any experience with this?

I will be respraying after I remove the section with die back, and the original section shot with the small Iwata gun (orange peel).

Thanks again, I am really excited to respray.

Patrick

[fj5gtx]

[QUOTE=Patrick_;452456]....Now, the only question I have is that I am trying to sand the old finish, but it keeps loading my paper after only a couple swipes... /QUOTE]

I'd let it bake in the sun for a couple days. Then, when the paint is cool again, try wet sanding with a little bit a liquid dish soap in the water. You may need to wait a while for the paint to cure more.

[bmarler]

B Marler,

Thank you so much for the advice. I picked up a cheap piece of sheet metal, primed it, and sprayed it with a 1.4mm tip. I had to reduce it to 10%, but the key was upping the pressure to ~30psi as you recommended. I was able to get much better atomization at the higher pressure.

Now, the only question I have is that I am trying to sand the old finish, but it keeps loading my paper after only a couple swipes. There was some orange peel in the original areas. I noticed that scotch brite (maroon) on a soft block will sand nicely without clogging, but the question is whether it will remove the peel? Do you have any experience with this?

I will be respraying after I remove the section with die back, and the original section shot with the small Iwata gun (orange peel).

Thanks again, I am really excited to respray.

Patrick

glad to hear you're getting dialed in with the paint work.
scotchbrite will not remove peel. it will lessen it to an extent, but to remove it entirely you need to block sand. it was mentioned to wet sand and i agree. let it cure as much as possible, then wet sand it.
if a small amount of peel is tolerable, you can try wrapping the scotchbrite around a block and see if will be good enough. i just don't have a good idea how fine you need the finish to be.

[Patrick_]

Thanks for the feedback. It sounds like waiting and wet sanding would be the best option, however I am strapped for time unfortunately. I just got confirmation that the new machine will be arriving next week, and I will have to break down my temporary paint booth to make room for it. I want to leave at least a week to cure, so I will have to respray in the next day or so. Last night, I was able to block sand some of the larger flat areas, I just used a lot of paper. I will finish up with the smaller areas with scotch brite and reshoot. This feedback will help temper my expectations.

Patrick

[Patrick_]

I wanted to report back that the respray went really well. The orange peel was minimal and I am very happy with the end result. After a day of drying/cure, the gloss is very nice as well. I would not have got there on my own, and I appreciate all the help along the way.