Cracks in finish, what did I do wrong?

[davionics]

Hello all,

I'm making a cabinet with drawers for my router table out of poplar and I ran into a problem during finishing. I sprayed two coats of Valspar waterbased semigloss interior paint/primer (black to match the table). Then I sprayed Minwax polycrylic, also semigloss. The first coat seemed fine until one drawer front looked like the finish cracked. I left the sanding dust to show up better in the picture. I think I sprayed the poly on too think and this caused the cracking but on the other hand I let it dry vertically so it would catch less overspray and I figured if I did spray too much why wouldn't it sag or run? I couldn't try to sand it out because I didn't want to sand through the paint so the sanding had to be a light touch. On the third coat it still didn't hide the cracks any but I did notice some areas where the poly went on heavy that it had a milkly look against the black paint. It wasn't as bad once it dried but it's still noticable.

 

I'm building one cabinet at a time as I build up my shop so I'm experimenting with everything from types of finishes to using screws versus dominos. I know I would have to sand everything down if this project really mattered but since it's in the shop, I'm done with the finishing.

 

So I don't make the same mistake again, any ideas as to what I did wrong? I'm hoping maybe someone has seen this before.

Thanks

Dave

[chicks82]

It looks to me that you did not allow the black paint dry long enough. So when it finished drying which was after the topcoat dried it pulled the top coat apart. That is the only thing i can think that would do this.

[AceHoleInOne]

Did this happen to the entire project or only to the drawer? What sheen is the black paint? Did you scuff the paint before you applied the topcoat?

Did you thin the paint and topcoat? How long did you let the paint dry before topcoat? Shop temp?

-Ace-

[davionics]

Did this happen to the entire project or only to the drawer? What sheen is the black paint? Did you scuff the paint before you applied the topcoat?

Did you thin the paint and topcoat? How long did you let the paint dry before topcoat? Shop temp?

-Ace-

 

Ace,

The finish turned milky in the heavy spots on the cabinet where I had to angle the spray gun and these areas had little cracking but this drawer was the worst. The areas actually show up against the black paint versus the other areas are just clear. The paint was semi gloss; I used a 360 wet/dry paper between coats; the paint I had to thin because it was really thick so I thinned it 4 parts paint, 1 water; I put the second coat of paint on about 4 hours and started the poly the next evening so 24hrs or so; I have the shop at 67 while I'm working in it and set it to 60 for the night while finish is drying, day to day in the winter I set it to 55.

 

The areas in question I know for sure were sprayed on heavy from not having a great light setup but I really thought I would have sagging.   I've never sprayed water based anything before so this is all new. I used the exact polycrylic but in gloss over a white paint and I didn't have any issues but it may have been harder to see over white.

 

Once the drawer was cleaned, I tried to polish it and wax it just to see what it would do but it did nothing other than make the surface smoother. Any ideas?

Thanks

Dave

[AceHoleInOne]

Ace,

The finish turned milky in the heavy spots on the cabinet where I had to angle the spray gun and these areas had little cracking but this drawer was the worst. The areas actually show up against the black paint versus the other areas are just clear. The paint was semi gloss; I used a 360 wet/dry paper between coats; the paint I had to thin because it was really thick so I thinned it 4 parts paint, 1 water; I put the second coat of paint on about 4 hours and started the poly the next evening so 24hrs or so; I have the shop at 67 while I'm working in it and set it to 60 for the night while finish is drying, day to day in the winter I set it to 55.

 

The areas in question I know for sure were sprayed on heavy from not having a great light setup but I really thought I would have sagging.   I've never sprayed water based anything before so this is all new. I used the exact polycrylic but in gloss over a white paint and I didn't have any issues but it may have been harder to see over white.

 

Once the drawer was cleaned, I tried to polish it and wax it just to see what it would do but it did nothing other than make the surface smoother. Any ideas?

Thanks

Dave

 

 

Sounds like the finish has blushed on you. Poplar is a very porous wood and the wood was probably still wet inside and tried to gas off through the topcoat. Try dusting a little  lacquer thinner over the topcoat and see if that opens up the finish to let the moisture out. Not familiar, with the chemistry of your products. But with other water-based products, the lacquer trick will work.

The other issue I see is the cold temps. Water-based like warm temps around 70 degrees. In addition, you already figured out you probably sprayed to

heavy. The first couple coats of water-based topcoat is best sprayed thin coats. Then apply a nice wet coat, should start to look blue.

I’m confused….did you spray over a drawer that you waxed?

 

I guess since this is shop cabinet, do nothing. Or if this were me, take it as learning experience,  strip everything and do over till you get it right.

 

Hope this helps?

 

-Ace-

[dwacker]

Looks to me like you just made a few mistakes with temp and dry times. For future reference Id stay away from improvised finishes. Every decent company makes a good black or white lacquer or poly in both solvent and waterbased. Target black is outstanding and sprays perfectly out of the can. GF Black base sprays great if you warm in up a little and the black poly top coat sprays great out of the can. Rodda and sherwin williams both have solvent based blacks that are tried and true and require almost no skill to spray. SW WB blacks are a little picky about temp but anything over 65 and a warmed up finish they go on glass smooth.

[davionics]

Looks to me like you just made a few mistakes with temp and dry times. For future reference Id stay away from improvised finishes. Every decent company makes a good black or white lacquer or poly in both solvent and waterbased. Target black is outstanding and sprays perfectly out of the can. GF Black base sprays great if you warm in up a little and the black poly top coat sprays great out of the can. Rodda and sherwin williams both have solvent based blacks that are tried and true and require almost no skill to spray. SW WB blacks are a little picky about temp but anything over 65 and a warmed up finish they go on glass smooth.

Making mistakes sometimes is the best teacher but I have some question if you don't mind so I don't keep making the same type of mistakes.

What did you see as my dry time mistake?

You mentioned Target black and GF black, I have no ideas what you're referring to...? I'm hoping to find one particular type or brand of paint and stick with it so your words of "outstanding" is worth a looking into.

If I want to do a coffee and end tables I would think poly would hold up the best. So if I want to use poly on this, why would I want to spray varnish or shelack? I'm thinking if I want to put a finish on a small box or  piece of furniture, why use anything other than poly? Maybe the drying time between coats? That's why I used lacquers in the past but I prefer to use something different now.

Thanks for you help with this...

Dave

[TRBaker]

Dave, it occurred to me that if you added 20% water, it would really effect your drying time. The next time you need to thin latex, add Flowtrol to it instead. Just follow the directions on the label.

[AceHoleInOne]

 

I think this is the General Finishes product mentioned above (GF Black) . Spray's  perfect, I have never had to warm it, as Particle Board suggested, could be improper gun setting on his part or his finishing room is too cold. This is a "thicker" product due to the pigments.

 

It has excellent coverage, and is sold through the pro side of their website. Just call them should you have any questions.

 

-Ace-

[dwacker]

 

I think this is the General Finishes product mentioned above (GF Black) . Spray's  perfect, I have never had to warm it, as Particle Board suggested, could be improper gun setting on his part or his finishing room is too cold. This is a "thicker" product due to the pigments.

 

It has excellent coverage, and is sold through the pro side of their website. Just call them should you have any questions.

 

-Ace-

This is the black base. They call it undercoat, it doesn't flow as nice as the black poly. Really any topcoat does better warmed rather than thinned. You get more finish down quicker. Warming reduces viscosity.

http://www.generalfinishes.com/professional-products/water-base-paints-glazes-and-pigmented-topcoats/enduro-black-white-undercoat#.UUMV_Yy9KK0

[dwacker]

Making mistakes sometimes is the best teacher but I have some question if you don't mind so I don't keep making the same type of mistakes.

What did you see as my dry time mistake?

You mentioned Target black and GF black, I have no ideas what you're referring to...? I'm hoping to find one particular type or brand of paint and stick with it so your words of "outstanding" is worth a looking into.

If I want to do a coffee and end tables I would think poly would hold up the best. So if I want to use poly on this, why would I want to spray varnish or shelack? I'm thinking if I want to put a finish on a small box or  piece of furniture, why use anything other than poly? Maybe the drying time between coats? That's why I used lacquers in the past but I prefer to use something different now.

Thanks for you help with this...

Dave

Dry time mistake, assuming it was dry. 24 hrs @ 70 degrees is perfect if you were painting a wall. But when you want to cover with a top coat with poly two maybe three day is more reality a week would be best. The finish cures over time and shrinks. It doesn't matter on your walls but will always cause problems with a topcoat. Wall paint is more so an improvised finish.

Target coating black and white base colors are a WB satin lacquers That are designed to be covered with a poly or other clears. They are mixed properly to be sprayed with woodworking equipment right out of the can. General finishes also has a black base along with a black poly, same thing there they are designed for woodworking.

The problem is your undercoat being improvised. Latex house paint is not a woodworking finish. Nor do house paint companies offer a poly that is 100% compatible. They all offer a undercoat or base that is compatible sherwin Williams, valspar, Roda all sell finishes made for the job. If you want Polly I'm not suggesting you spray shellac. I'm suggesting you use finish that is known to be compatible and made for the job.

[dwacker]

Some reading from pros that do nothing but finishing.

http://woodfinishings.wordpress.com/?s=Heating

Annex is the place to call for finishing products and real info. Shipping is expensive but the advice is free.

[AceHoleInOne]

This is the black base. They call it undercoat, it doesn't flow as nice as the black poly. Really any topcoat does better warmed rather than thinned. You get more finish down quicker. Warming reduces viscosity.

http://www.generalfinishes.com/professional-products/water-base-paints-glazes-and-pigmented-topcoats/enduro-black-white-undercoat#.UUMV_Yy9KK0

 

FYI...an undercoat is meant to build quickly filling voids and sand easy. Not designed to be a pigmented topcoat. Also an undercoat will serve to even a base color and help pigmented topcoat opaqueness which can be problematic.

 

The General Finishes undercoat can be thinned up to 20% with water. Warm temperatures with water based are key and 60 degrees is about the lowest you want to go. Water-based has to evaporate the water, it takes a lot longer in lower temps, hence causing you potential finishing issues. So its either air movement or warm temperatures, to evaporate the water. 

 

Oh I found an old link about heating finishes, to make them thinner.

 

-Ace- 

 

[dwacker]

FYI...an undercoat is meant to build quickly filling voids and sand easy. Not designed to be a pigmented topcoat. Also an undercoat will serve to even a base color and help pigmented topcoat opaqueness which can be problematic.

 

The General Finishes undercoat can be thinned up to 20% with water. Warm temperatures with water based are key and 60 degrees is about the lowest you want to go. Water-based has to evaporate the water, it takes a lot longer in lower temps, hence causing you potential finishing issues. So its either air movement or warm temperatures, to evaporate the water. 

 

Oh I found an old link about heating finishes, to make them thinner.

 

-Ace- 

 

Ya I know its a base coat and thats why it doesnt flow as well. Its more like a primer than anything else. GF base is just that its a base thick and full of solids. Target is fine as a top coat but is only satin and needs a top clear to get a good shine. Target changed their formula so it can be used as a base or a complete finish. I switched over completely to WB back in Nov of last year. I guess water is going to be all that is left real soon so better get used to it. I completely revamped my finishing approach to make it much easier albeit more expensive. What Ive found is to keep the shop at close as possible to 70, use an infared thermometer to make sure wood is close to room temp but 98 is even better and heat finish to body temp almost 100. If you stick to this no thinning is needed at all. The finish flows better and you get a done in half the time. I have cheap aircraft sump heaters that heat the finish and just ordered a Kremlin inline wall mount heater to go on the pressure pot. A good affordable finish heater is a cloths iron clamped upside down, cheap and most folks have one.

Colored solid finishes are easy with the right products. Most white bases can be tinted to match any color by any paint store even Home Depot. Home Depot will tint white bases like target 6500 for free. SW charges $2 a gallon I just sprayed an ugly baby shi$ brown kitchen last week with em6500 and cic wb poly no sanding no extra work although a very ugly color the finish was great. Ive been doing alot of black for a local Salt water aquarium store with EM6600 and elcheapo minwax wb poly because they dont spend money. All things considered even the minwax turns out perfect over the right type of base. I did a bath vanity back in Jan with GF black base and black poly and would not use it again in a high traffic area, it isnt holding up well.

[AceHoleInOne]

=>    All things considered even the minwax turns out perfect over the right type of base. I did a bath vanity back in Jan with GF black base and black poly and would not use it again in a high traffic area, it isnt holding up well.

 

That holds true with all high traffic areas. Reason why some manufactures suggest for those situations, a good cross-linked topcoat over a pigmented finish for extra durability. Always be mindful to match the finish to the use. Wonder if you introduced the vanity to service to soon and the coating was still curing? The coating has passed KCMA. So its a quality product. If I were you, give your General Finishes REP., a call.

 

Hope this helps.

 

 

-Ace-

[davionics]

Thanks all but I'm almost getting too much info...lol. I'm seeing undercoat and basecoat and topcoats.

 

So give me the monkey version,

 

If I want to color a project using WB products I would raise the grain first then...

spray a base coat of what? clear poly or the paint?

Then spray on the black poly?

then spray on a topcoat of clear poly?

 

so why the 3 processes? Can I just spray the GF black poly for all 3?

 

Thanks

Dave

[davionics]

Dry time mistake, assuming it was dry. 24 hrs @ 70 degrees is perfect if you were painting a wall. But when you want to cover with a top coat with poly two maybe three day is more reality a week would be best. The finish cures over time and shrinks. It doesn't matter on your walls but will always cause problems with a topcoat. Wall paint is more so an improvised finish.

Target coating black and white base colors are a WB satin lacquers That are designed to be covered with a poly or other clears. They are mixed properly to be sprayed with woodworking equipment right out of the can. General finishes also has a black base along with a black poly, same thing there they are designed for woodworking.

The problem is your undercoat being improvised. Latex house paint is not a woodworking finish. Nor do house paint companies offer a poly that is 100% compatible. They all offer a undercoat or base that is compatible sherwin Williams, valspar, Roda all sell finishes made for the job. If you want Polly I'm not suggesting you spray shellac. I'm suggesting you use finish that is known to be compatible and made for the job.

Ok, I had to re-read all of this again. So the Target coating I would spray on as a base and then apply the clear poly to get a gloss finish. How many coats of the base are generally required?

 

I went to the Target web site and the shipping alone for a gallon is $18 to Ohio so how does Target compare to GF which I can get at a local woodcraft store?

Thanks again for all the help...

Dave

[AceHoleInOne]

Thanks all but I'm almost getting too much info...lol. I'm seeing undercoat and basecoat and topcoats.

 

So give me the monkey version,

 

If I want to color a project using WB products I would raise the grain first then...

spray a base coat of what? clear poly or the paint?

Then spray on the black poly?

then spray on a topcoat of clear poly?

 

so why the 3 processes? Can I just spray the GF black poly for all 3?

 

Thanks

Dave

 

Can I just spray the GF black poly for all 3      Yes you can.

 

 

 

1.Undercoat is great for sealing mdf or grainfilling wood to get a piano smooth finish and as a base color under other pigmented topcoats.

2.The pigmented clear poly from General Finishes is fine by itself.

3.A topcoat of a waterbased will provide the finish extra protection should the piece receive a lot of action. Some folks do, some don't.

 

-Ace-

[dwacker]

Ok, I had to re-read all of this again. So the Target coating I would spray on as a base and then apply the clear poly to get a gloss finish. How many coats of the base are generally required?

I went to the Target web site and the shipping alone for a gallon is $18 to Ohio so how does Target compare to GF which I can get at a local woodcraft store?

Thanks again for all the help...

Dave

I doubt you will find it at woodcraft. There are a couple dealers in Ohio check their professional dealer locator. Target usually works out to be cheaper if you need to ship.

Your going to use alot more finish with just poly.

[davionics]

Here's my thinking on using poly, use it for areas that will take a beating such as floors, end tables etc. so are there any advantages to using varnishes and shellacs? I guess I'm tyring to keep this simple and if i only use poly for all things like small boxes or general projects. I know I would want to go with lacquer if I were doing a set of cabinets to take advantage of the drying time.

 

I guess in a perfect world I would have one finish, 4 different grits of sandpaper and do the same thing each time for a perfect finish...lol. Maybe i'll start another topic on this...

 

Thanks everyone for the tips on the cracking. It does seem as if the temp was the issue. Also I'll be trying both the GF and Target poly's to see which I like best.

Dave

[jHop]

Dave, you mention Ohio.... You might have solved your dry time issue with that one word...

 

In my experience, the best time to dry in Ohio (if you do not have an enclosed and heated shop) is June/July... unless it rains.  Then your best bet is to move.  Closer to the lake or the river, I'd add easily an extra day in when figuring time.  (Then again, I have an outdoor shop, so I'm slightly handicapped by finishing...)