Sanding color coat before clear, pigtails persist

[jhaley]

Pretty sure this has already come up here, but no luck searching.

Love my ETS/3 but sometimes I simply cannot avoid making curlicues, pigtails. I clean my abrasive regularly, don't let it load up, and change often.  Hard to see the pigtails on bare wood or in a color coat but put clear over it and boom! I have to sand off the clear coat and hand sand.

I have tried different backing pads - hard and soft - and different materials, abranet, brilliant, and 3M finishing film. 400 to 800 grit. 3M is best, but the pigtails persist, and lack of dust removal - the 3M discs are not hole punched - is a pain.

It takes a special lighting to see the pigtails in the color coat but any lighting will show them after clear coat.

I don't always have the problem. But I do now with parts of the current black project. I'm at the clear coat stage and cannot eliminate the pigtails. Already sanded off a first clear coat from a portion of the project - some is OK - and reapplied color.

I can't hand sand the color coat because that will not give the uniform satin/gloss needed under clear. Have to be careful even wiping dust off or I make shiny marks in the satin.

Had the problem with water based polyethylene and water based acrlylic lacquer, Target Coatings EM 6000 and 6600.

Could be happening because coating is soft. May get better results - sometimes it is not a problem - when I wait longer - longer than overnight, way longer - to sand, but that sure slows down a project, and I certainly don't want to wait just because it might help. Instructions say can sand after a couple hours, and that sometimes seems to work fine.

Ideas?

Thanks,

John H.

 

[Alan m]

welcome to the fog
it sounds like the finish isnt cured fully
what temperature is your work area.
is there  good airflow to . sometimes getting rid of the gases helps the finish off gass faster

 

[semenza]

Hi John,

Welcome to the FOG!  [smile]

I suspect from your description that Alan is right that the finish needs to be cured more before sanding. Maybe do a little purposeful testing to determine if that is the case.

Seth

 

[junk731]

Any chance the pigtails are there before the colour is applied. Without knowing your sanding schedule it makes it hard to help. What are you using for your colour coat?

John

 

[tjbnwi]

I have the ETS 125, no problems like this.

Is there one species of wood you are having more trouble with?

This type of problem almost always comes down to technique. I know someone who can't stand the RTS due to fisheyes and tails. I've used his sander, no problem at all.

Tom

 

[tiralie]

Love my ETS/3 but sometimes I simply cannot avoid making curlicues, pigtails. I clean my abrasive regularly, don't let it load up, and change often.  Hard to see the pigtails on bare wood or in a color coat but put clear over it and boom! I have to sand off the clear coat and hand sand.

I have had curlicues and pigtails after using my ETS/3 on any hard wood e.g. Maple and it is almost always because I let the machine "walk" or run on the surface rather than guide it, and had the vacuum on too high. This is usually a result of rushing the sanding and missing one or all of the sanding grits required...because I hate sanding.

Could be happening because coating is soft.

How are you applying the finish spray, brush etc.? What are the conditions you are finishing in? Is it warm enough in your shop to cure these coatings? An ambient temperature lower than 60degrees creates problems for waterborne coatings.

 

[Scott B.]

In addition to the above suggestions, I would add:

I don't sand the stain coat, at all. Not a good idea. Do all sanding prior to applying color. Then resume after first clear coat to build the finish.

Critical: Before applying color, wipe down surface with a lint free rag damp with thinner and put an inspection light on it (syslite, or other LED, not halogen). This will reveal any cosmetic flaws from sanding prior to initiating finish.

As Tim noted, it takes discipline and good habits to not skip a step in the transition from prep sanding to finish building.

 

[peter halle]

I am reading the original post that the issue is with an automotive paint system - color coat and then clear coat.  Is this correct?  Would the answers and advice given be different if this were correct versus a similar wood situation?

Peter

 

[jhaley]

Wow! Many thanks for all the replies -

Responding to some of the questions/suggestions:

-As to the material not being sufficiently cured, that is my gut feeling. But there's little satisfaction in that, because it doesn't make sense. While Target says 30 to 60 days (also seen longer-is-better and 100 hours) before rubbing out the final topcoat, it's two hours to sand between coats. Q: Has anyone heard or found different on that?

And it seems it sometimes cures and sometimes doesn't, doesn't for a long time. When I first ran into this it was way before clear coat stage, with Target's HSF5100 filler. Two hours to sand, but suddenly even after days couldn't sand. Paper immediately loaded, and badly. Had to simply back off from project. Lost track of the time, months I think.

Later resumed but with abranet, and have stayed with abranet. Yesterday tried some new Platin 2 with some luck, but still discouraging.

I can wait, though no one likes to, but it's really difficult to wait without knowing how long or even whether that's the issue. Plain stuck right now.

Also, the wife is peeved. Project's been in the shop since a year ++ before we married last summer, and she wants me to "slap a coat of paint on it" and bring it home. It's to replace the folding table with-black-sheet-on-it that's under the big plasma now.

-Air flow is excellent, Have two fans. Ceiling vents to outside,  can draw air from entire climate controlled building or also from outside thru wall (fan, vents, filter) in shop. Only use that in prime weather or when not spraying to clear room quickly. Also have Jet filter system overhead to clean air before spraying. No dedicated booth, just lots of curtains.

-Temperature is kept high 60s or 70 and above. Humidity 40 to 60%. This is SW GA.

-As to technique, I'm no whiz with finishes - hate that part of building - but I've always thought I could sand.

-As to not sanding the color, do all sanding prior to color, I can't spray that well! Got to address the defects. Sometimes very, very few, sometimes a mess. I sand to perfection (smooooth) and then ruin it with finish. Up to now.

-The wood is red oak. And, yes I'm shooting for close to piano black! Like to make things hard for myself, plus, there's no specialty lumber yard hereabouts. Coulda shoulda used poplar, though.

-As to wiping with thinner, this water based material sometimes doesn't like water even when ready to sand, so I just use a tack cloth or, now that things are critical, a microfiber cloth, untreated. Did have some problems with fisheye before the microfiber, but knock-on-wood none since.

-Lights, have lots, plus use a strong led flashlight and magnifier.

John H.

 

[tiralie]

As to the material not being sufficiently cured, that is my gut feeling. But there's little satisfaction in that, because it doesn't make sense. While Target says 30 to 60 days (also seen longer-is-better and 100 hours) before rubbing out the final topcoat, it's two hours to sand between coats. Q: Has anyone heard or found different on that?

No I have not heard different. That sounds right. How much are you thinning your topcoat? What are you using to rub out the top coat?

And it seems it sometimes cures and sometimes doesn't, doesn't for a long time. When I first ran into this it was way before clear coat stage, with Target's HSF5100 filler. Two hours to sand, but suddenly even after days couldn't sand. Paper immediately loaded, and badly. Had to simply back off from project. Lost track of the time, months I think.

Hard to say but it sounds like your coating (HSF5100) was applied to thick and/or your sanding is overheating and softening the coating. Do you use a wet mil gauge when spraying?

Later resumed but with abranet, and have stayed with abranet. Yesterday tried some new Platin 2 with some luck, but still discouraging.

What coating was this done on? The 6600 or the HSF5100?
BTW, the 6600 is a self priming coating so you should be able to skip the priming step.

I can wait, though no one likes to, but it's really difficult to wait without knowing how long or even whether that's the issue. Plain stuck right now.

Also, the wife is peeved. Project's been in the shop since a year ++ before we married last summer, and she wants me to "slap a coat of paint on it" and bring it home. It's to replace the folding table with-black-sheet-on-it that's under the big plasma now.

Sorry, can't help you there I am in deep s**t on a regular basis.

-Air flow is excellent, Have two fans. Ceiling vents to outside,  can draw air from entire climate controlled building or also from outside thru wall (fan, vents, filter) in shop. Only use that in prime weather or when not spraying to clear room quickly. Also have Jet filter system overhead to clean air before spraying. No dedicated booth, just lots of curtains.

-Temperature is kept high 60s or 70 and above. Humidity 40 to 60%. This is SW GA.

All above sounds good.

-As to not sanding the color, do all sanding prior to color, I can't spray that well! Got to address the defects. Sometimes very, very few, sometimes a mess. I sand to perfection (smooooth) and then ruin it with finish. Up to now.

What equipment/setup are you using for spraying?

-The wood is red oak. And, yes I'm shooting for close to piano black! Like to make things hard for myself, plus, there's no specialty lumber yard hereabouts. Coulda shoulda used poplar, though.

Using Oak could be you biggest problem. Not only is it adding a step in applying the grain filler the additional sanding isn't helping. I have not used  Have you tried the system three epoxy grain filler? I think they might work better for this application.

-As to wiping with thinner, this water based material sometimes doesn't like water even when ready to sand, so I just use a tack cloth or, now that things are critical, a microfiber cloth, untreated. Did have some problems with fisheye before the microfiber, but knock-on-wood none since.

You should never use a tack cloth when spraying water borne coatings and regularly create fish-eyes in the coating. Tack clothes are only to be used with solvent based coatings.
You can wipe down with a rag soaked in distilled water or an alcohol/water solution such as Methyl hydrate. The Alcohol based solution will blow the sheen and if applied too heavily or pooled, will soften the surface of the coating so you will need to let it dry and then you can coat.

 

[Scott B.]

-As to not sanding the color, do all sanding prior to color, I can't spray that well! Got to address the defects. Sometimes very, very few, sometimes a mess. I sand to perfection (smooooth) and then ruin it with finish. Up to now.

John H.

Not sure I follow. Are you spraying stain? If so, take that out of the equation. Go to a gel stain or wiping stain, then just spray your clear. Point is, don't sand your stain coat. Go straight from stain to clear, then resume scuff sanding between clear coats.

 

[tiralie]

John:
Maybe we can help if we know your recipe
I am assuming that your schedule is as follows:
Sand to smooth
Apply target hsf5100
Sand (not scuff)
Apply 6600
Sand (not scuff)
Apply 6000
Buff
See pigtails and curlicues

Is this correct?

 

[tjbnwi]

I am reading the original post that the issue is with an automotive paint system - color coat and then clear coat.  Is this correct?  Would the answers and advice given be different if this were correct versus a similar wood situation?

Peter

Peter,

The new automotive finish colors are never. I shuddered when I read this.

This was sanded with an ETS125. No fisheyes or tails. By the way, true piano black is done over a cloth base.

Tom

 

[jhaley]

Ah! Class is in session again! Going to be tricky to respond to all the help offered without creating a monster off-putting message. here goes:

On Tim's first points (if I understand the postings right):

-As to wiping, Methyl hydrate alcohol/water? New to me. Sounds good, and if too much softens  the finish (barely - I've seen what plain water can do if the finish isn't ready) that might help with any sanding scratches? I'm a little disappointed the clear doesn't soften the color enough to smooth them at all, especially if the color finish is insufficiently cured, as uncured or too-soft-to-sand finish appears to be the prime scratch culprit.

Minor off-topic: I sometimes encounter pits that seem to reject finish. Not fisheyes, irregular shape, hard sharp "cliff" borders. Some big ones appear mechanically - a run being scraped takes the finish under with it, but much smaller ones, sometimes in groups, appear for "no reason," must be chemical somehow, just find them after a coat. They continue to reject filling, possibly a feature of surface tension, and sanding down risks sanding thru so I've been looking for something to wipe the area with to aid filling. To remove any chemical and reduce surface tension. Can't sand inside the pit and slick finish inhibits runout vs sanded area. The Methyl Hydrate should help? Been trying Toluene.

-About tack rags being a no-no on water, thanks, didn't know, conforms to my observations of fisheye occurrence.

-As to what coating I'm using abranet and platin 2 on, it's EM6600, or that's where the sanding issue is now. But started the abranet on HSF 5100. The 5100 is filler, mine was tinted black. It was replaced by HSF 5000, not offered in black. Clear or Gray. Used Gray. Bad move. Sand thru's are really ugly now.

-Re system three epoxy grain filler - funny you ask. Filling with 5100 on red oak was a bitch. I did try the system three thickener. Mixed it with the 5100 at different rates. Found it difficult to mix, harder to work with, and no help in filling.

-Equipment/setup: Jeff Jewitt's recommendations, Walcom pressure pot and Genesi HVLP gun 1.2 nozzle set, driven by big (plenty of) IR compressor drawing indoor (conditioned) air on 80 gal tank with regulator, water trap, etc. Compressor and line drained daily.

Got sick of cleaning pot, having to change colors black to clear and back, because I'm having to go back and apply more black at this stage. Touch-up, sand thru, etc. So last week I got a Sata 4000 HVLP gravity cup gun and I'm using that for the black.

No dedicated spray booth, just lots of curtains, shop in air conditioned building, ceiling exhaust fan, can draw air from building or with a second wall fan (filtered, louvered) from outside. Only run outside air if weather perfect. Temp high 60s to 80, humidity 40-60%. SW GA.

-Coating too thick - that's possible. But I'm usually aware of it -happens in places sometimes and I can see it.  Shouldn't make the cure of a whole coating just stop. Mil gauge - yes, but not religiously. 2-3 mils was recommended on 6600, and that's where I am when I check.

-Thinning topcoat, no. And I'm not to rubbing yet, got lots of material on hand for that, don't know what I'll use.

Q was not about time to wait to rub, just about time to wait to sand out last color coat in preparation for clear coat. I said my understanding was you could sand EM6600 after two hours - is that what were addressing with "that sounds about right?" That's the key question. How long should it be.

Scotts's point:

-About not sanding the color coat, using stain - No stain involved here. Lots of filler, a shellac barrier coat, lots more filler, then color (Target Coating's EM6600, directions say spray) sprayed, to be followed by EM 6000 high gloss clear top coat.

My spraying requires sanding of defects. At least prior to clear coat, which is where I am. If I have one defect and sand that, to get an even sheen before clear coat I have to sand the whole thing, right?

Tim's second post, re schedule:

You asked if this was my schedule:

I am assuming that your schedule is as follows:
Sand to smooth
Apply target hsf5100
Sand (not scuff)
Apply 6600
Sand (not scuff)
Apply 6000
Buff
See pigtails and curlicues

Not quite. No buffing/rubbing yet. That will come after last clear coat and a long cure. And not sure what "sand (not scuff)" means. Not sanding just for adhesion.

My summary procedure:

1-Sand wood to smooth.
2-Add hsf5100 (tinted black) to fill grain, usually with a brush.
3-Wipe off excess.
4-Sand to level and eliminate defects/brush marks. Using 400 grit mainly
5-repeat last 3 steps many times
6-Per Jeff at target coatings, lay down a shellac barrier coat
7-Repeat steps 2-4 but wipe less sand more to get build.
8-Change filler to improved version HSF 5000 in gray (black na)
9-Repeat 7 till satisfaction balances frustration, seeing lines that were gone - sanded out - reappear continually as coating shrinks (whatever, they reappear after they're gone).
10-Spray first coat of EM 6600 black as color coat.
11-Sand as #4
12-Spray second (at  least) coat of color
13-Sand as #4, but somewhat finer, mostly to 600, more care, with special attention to uniformity of appearance (sheen).
14-Spray EM 6000 high gloss clear coat.
14-Sand back down to color and resand it as necessary where gloss reveals sanding lines, mainly pigtails.

That's where I am. Some clear coat has gone well but in other areas - critical areas - I just cannot achieve satisfactory sanding results. Not for gloss clear coat.

Prime suspect is uncured finish but makes no sense it won't cure overnight - even several days now - and how long do I wait?


Tom's post to Peter-

I believe color coat and then clear coat may be automotive terminology. But I'm not using automotive materials, also not sure what you were reacting to about them. Almost wish I was using automotive materials.

About true piano black being over fabric, never heard that. Interesting. Beautiful work in the photo (which for some reason I can't see now).

Many thanks to all!

 

[tjbnwi]

jhaley, thanks for the compliment.

There is a big difference between sanding wood to smooth and sanding wood to finish.

This is pine sanded to 150 (actually 150 is the only grit I used) with the RTS. I took the photo of the corner so you can see even with opposing grains, a pigtail free surface can be accomplished. Practice, you'll get it. Gloss black is not easy.

Tom

 

[tiralie]

Ah! Class is in session again! Going to be tricky to respond to all the help offered without creating a monster off-putting message. here goes:

John
First off thanks for posting and responding to the questions here. I am having fun and learning which after all is why I love the FOG. I saw your post on the Target site, so I hope Jeff can help you there.

On Tim's first points (if I understand the postings right):

-As to wiping, Methyl hydrate alcohol/water? New to me. Sounds good, and if too much softens  the finish (barely - I've seen what plain water can do if the finish isn't ready) that might help with any sanding scratches? I'm a little disappointed the clear doesn't soften the color enough to smooth them at all, especially if the color finish is insufficiently cured, as uncured or too-soft-to-sand finish appears to be the prime scratch culprit.

Try to clean with distilled water first, and experiment with the thinned alcohol before you go ahead with your main project.
EM 6000 should burn into the EM 6600 no problem so if you are having problems there I think that's why you are seeing the curlicues and pigtails.

Minor off-topic: I sometimes encounter pits that seem to reject finish. Not fisheyes, irregular shape, hard sharp "cliff" borders. Some big ones appear mechanically - a run being scraped takes the finish under with it, but much smaller ones, sometimes in groups, appear for "no reason," must be chemical somehow, just find them after a coat. They continue to reject filling, possibly a feature of surface tension, and sanding down risks sanding thru so I've been looking for something to wipe the area with to aid filling. To remove any chemical and reduce surface tension. Can't sand inside the pit and slick finish inhibits runout vs sanded area. The Methyl Hydrate should help? Been trying Toluene.

I wouldn't (don't) use Toluene or Lacquer thinner it softens latex paint. My understanding is that it is to be used only with solvent based coatings and can affect waterbase coatings. I wouldn't be surprised if this isn't causing the coatings to not cure properly.
Are you washing/cleaning your lines with Toluene?
You should be able to sand the run out, and then recoat with the 6600 without any problem. If it's not curing properly that's a different problem.

-As to what coating I'm using abranet and platin 2 on, it's EM6600, or that's where the sanding issue is now. But started the abranet on HSF 5100. The 5100 is filler, mine was tinted black. It was replaced by HSF 5000, not offered in black. Clear or Gray. Used Gray. Bad move. Sand thru's are really ugly now.

Based on what I understand of your process, I don't see why some burn through here and there would make any difference other than the inconvenience of having to spray another coat.

-Re system three epoxy grain filler - funny you ask. Filling with 5100 on red oak was a . I did try the system three thickener. Mixed it with the 5100 at different rates. Found it difficult to mix, harder to work with, and no help in filling.

Good to know, I have not used it. I have had good luck using West systems epoxy, but you do have to work fast once it's mixed.

-Equipment/setup: Jeff Jewitt's recommendations, Walcom pressure pot and Genesi HVLP gun 1.2 nozzle set, driven by big (plenty of) IR compressor drawing indoor (conditioned) air on 80 gal tank with regulator, water trap, etc. Compressor and line drained daily.

IR makes good compressors. What is the CFM rating on yours?

Got sick of cleaning pot, having to change colors black to clear and back, because I'm having to go back and apply more black at this stage. Touch-up, sand thru, etc. So last week I got a Sata 4000 HVLP gravity cup gun and I'm using that for the black.

Those SATA guns are nice! The Festool of spray guns. I have had my eye on a 1000K RP, but I am not set up to supply enough CFM to make the best use of those guns.

No dedicated spray booth, just lots of curtains, shop in air conditioned building, ceiling exhaust fan, can draw air from building or with a second wall fan (filtered, louvered) from outside. Only run outside air if weather perfect. Temp high 60s to 80, humidity 40-60%. SW GA.

Based on what you have written, it doesn't sound like this is an area of concern.

-Coating too thick - that's possible. But I'm usually aware of it -happens in places sometimes and I can see it.  Shouldn't make the cure of a whole coating just stop. Mil gauge - yes, but not religiously. 2-3 mils was recommended on 6600, and that's where I am when I check.

Ya, I agree. I think it's Toluene and or silicon contamination some where. I know, I know I am grasping at straws here.

-Thinning topcoat, no. And I'm not to rubbing yet, got lots of material on hand for that, don't know what I'll use.

Ok, I can't help you there.

Q was not about time to wait to rub, just about time to wait to sand out last color coat in preparation for clear coat. I said my understanding was you could sand EM6600 after two hours - is that what were addressing with "that sounds about right?" That's the key question. How long should it be.

Yes, you can scuff the EM6600 with a scotch brite pad in 2 hours no problem. I regularly do this with 6500 which is the same as 6600 except it's white.

-About not sanding the color coat, using stain - No stain involved here. Lots of filler, a shellac barrier coat, lots more filler, then color (Target Coating's EM6600, directions say spray) sprayed, to be followed by EM 6000 high gloss clear top coat.

My spraying requires sanding of defects. At least prior to clear coat, which is where I am. If I have one defect and sand that, to get an even sheen before clear coat I have to sand the whole thing, right?

No you don't have to sand the whole thing. You are making extra work. You do need to scuff to re-coat but EM6000 burns into EM6600.

Not quite. No buffing/rubbing yet. That will come after last clear coat and a long cure. And not sure what "sand (not scuff)" means. Not sanding just for adhesion.

Scuffing really is just creating a "tooth" for the next coating to adhere to. Essentially you are just scratching the surface to help the next coat stick versus taking off significant layer as sanding would. I just use a scotch brite (generic) pad and rough up the surface by hand.

My summary procedure:

1-Sand wood to smooth.
2-Add hsf5100 (tinted black) to fill grain, usually with a brush.
3-Wipe off excess.
4-Sand to level and eliminate defects/brush marks. Using 400 grit mainly
5-repeat last 3 steps many times
6-Per Jeff at target coatings, lay down a shellac barrier coat
7-Repeat steps 2-4 but wipe less sand more to get build.
8-Change filler to improved version HSF 5000 in gray (black na)
9-Repeat 7 till satisfaction balances frustration, seeing lines that were gone - sanded out - reappear continually as coating shrinks (whatever, they reappear after they're gone).
10-Spray first coat of EM 6600 black as color coat.
11-Sand as #4
12-Spray second (at  least) coat of color
13-Sand as #4, but somewhat finer, mostly to 600, more care, with special attention to uniformity of appearance (sheen).
14-Spray EM 6000 high gloss clear coat.
14-Sand back down to color and resand it as necessary where gloss reveals sanding lines, mainly pigtails.

That's where I am. Some clear coat has gone well but in other areas - critical areas - I just cannot achieve satisfactory sanding results. Not for gloss clear coat.

I think, (others may disagree), but the only layer you really need to worry about is the one you are gonna buff. As mentioned above the EM6000 should burn into the 6600 and cover any scratches etc. unless they are really deep.

Prime suspect is uncured finish but makes no sense it won't cure overnight - even several days now - and how long do I wait?

Under the conditions you mention, if it's not cured enough in two hours to scuff and re-coat, I think something else is wrong. Typically 6600 and 6000 will take 100hrs. to cure, so you have a fairly wide window for additional coats.

Tim

 

[jhaley]

I'm a bit on the run right now, and may respond to more points later, but for  now:

Tim, re you comment:
-Ya, I agree. I think it's Toluene and or silicon contamination some where. I know, I know I am grasping at straws here.

No fisheye problem since stopped with the tack rags. And I have never wiped with Toluene or anything, just lately tried dabbing deep problem spots before recoating, trying to make the surface accept the finish better. So can't be the Toluene.

Now using the alcohol and water for spot pretreatment. Have never wiped whole areas with anything after a bad experience with plain damp rag. Another reason I'm hung up on occasional (irrational!) slow cure as problem. Doesn't usually happen, but once is enough. Finish softened immediately with just the damp rag. And I've had the experience of accidental drops of water being on the surface of some 6600 (cured I don't know how long but surely a couple hours) for a few minutes just taking all the material under it when wiped off.

I don't think the scratches are chemical related at all. except possibly - see next comment.

You wrote:
No you don't have to sand the whole thing. You are making extra work. You do need to scuff to re-coat but EM6000 burns into EM6600.

If we're really on the same page, this is a revelation.

My impression is that laying down clear on top of color is like putting a piece of glass on top of it. If the underlying color isn't perfectly uniform you'll see  it. Unsanded flaws will show and scuffed areas will look scuffed.

There's a bond whether you scuff or not, but the burn in does not alter or blend the appearance of the 6600 surface. Wish it did, actually hoped it would, somewhat, but it's not my experience.

Also, if recoating within 24 hours directions say get burn in (bond I mean) with no need to scuff. Seriously off topic: I have read, in Bob Flexner's work , that scuff for bond is a myth. Maybe I believe it, but if the job is critical I'm going to follow directions, which is usually scuff when outside of recoat window, 24 hours (supposedly) for 6600.

I need to experiment, but this project is turning into one side issue after another when it needs to move forward!

I really don't have to sand the final color coat to a uniform appearance before clear coat?

And this is not really important, but re your comment "Based on what I understand of your process, I don't see why some burn through here and there would make any difference other than the inconvenience of having to spray another coat." The inconvenience comes in with having to go back to color because of the gray showing. If it was just the black filler I don't think I'd see it. Not much issue with witness lines.

Now that I have two guns going it's not so bad. But when I had areas of the project ready for more clear and sanded thru to gray somewhere it was frustrating. The pot . . ..

Oh, and for cleaning the pot and material line I just blow/drain the material hose into the pot, use plain hose water, followed by warm soapy water and scrubbing, then using pot pressure to push it thru the disconnected fluid line, then spraying such and then doing it all again with plain water. No chance of chemical contamination there.

 

[tiralie]

John:
Hopefully you have seen Jeff (Weiss - President of Target Coatings) who said that EM6600 can be lightly sanded after 2hrs., but doesn't cure as fast as the 6500 or their clear coats. He (Jeff) suggests that you wait at least 12-18hrs for a final sanding. They have a new formulation in production that dries faster.

Last time I created a black top (counter) using Oak veneer I used ebony dye with 2 coats of EM 6000 and one coat of SC9000.

Now using the alcohol and water for spot pretreatment. Have never wiped whole areas with anything after a bad experience with plain damp rag. Another reason I'm hung up on occasional (irrational!) slow cure as problem. Doesn't usually happen, but once is enough. Finish softened immediately with just the damp rag. And I've had the experience of accidental drops of water being on the surface of some 6600 (cured I don't know how long but surely a couple hours) for a few minutes just taking all the material under it when wiped off.

Well, certainly the slow cure times explains this...somewhat. I believe you, I still find it surprising. Doesn't give me a lot of confidence in EM 6600. Here is the post (jimtobias - end table ) with a reference to using DNA (denatured alcohol and distilled water on a black lacquered top.

You wrote:
No you don't have to sand the whole thing. You are making extra work. You do need to scuff to re-coat but EM6000 burns into EM6600.

If we're really on the same page, this is a revelation.

My impression is that laying down clear on top of color is like putting a piece of glass on top of it. If the underlying color isn't perfectly uniform you'll see  it. Unsanded flaws will show and scuffed areas will look scuffed.

There's a bond whether you scuff or not, but the burn in does not alter or blend the appearance of the 6600 surface. Wish it did, actually hoped it would, somewhat, but it's not my experience.

Also, if recoating within 24 hours directions say get burn in (bond I mean) with no need to scuff.

This works with EM6500 coated with EM 6000. Obviously EM 6600 is reacting differently. When I coated my black top, after buffing (sanding lightly) with a scotch bright pad I saw no evidence of scratches.

I need to experiment, but this project is turning into one side issue after another when it needs to move forward!

Ya, I understand...you could be screwing around for another week on that top. I think at this point I would cut my losses, toss the top and rebuild the top with some Maple and finish with some ebony dye, EM6000 and SC9000 buff/polish and be done.

I really don't have to sand the final color coat to a uniform appearance before clear coat?

Well if EM6600 acted the same as EM6500, then this would be true.

And this is not really important, but re your comment "Based on what I understand of your process, I don't see why some burn through here and there would make any difference other than the inconvenience of having to spray another coat." The inconvenience comes in with having to go back to color because of the gray showing. If it was just the black filler I don't think I'd see it. Not much issue with witness lines.

Now that I have two guns going it's not so bad. But when I had areas of the project ready for more clear and sanded thru to gray somewhere it was frustrating. The pot . . ..

Sorry what I meant was, at least you don't have to strip or trash the whole top and rebuild. Ya it's a pain and inconvenient to have to re coat particularly when projects are backing up.

Thanks again for posting. I learned a lot.
Tim

 

[tjbnwi]

Tim,

Thank you for taking the time to respond to John. I don't recall ever using a Target product, but I sure have learned a lot about them.

Just wanted you to know John is not the only one who appreciates your willingness to share your knowledge.

Tom

 

[peter halle]

Tim,

Thank you for taking the time to respond to John. I don't recall ever using a Target product, but I sure have learned a lot about them.

Just wanted you to know John is not the only one who appreciates your willingness to share your knowledge.

Tom

+1000 or more

Thanks Tim.