Bandsaw Restoration #4: Another Short Update, and Why I Hate Spray Paint

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Blog entry by Jimi_C posted 04-18-2010 06:25 AM 3006 reads 0 times favorited 10 comments Add to Favorites Watch
« Part 3: Quick Update Part 4 of Bandsaw Restoration series Part 5: Starting Reassembly - Finally! »

So, I thought everything was going along great, things were looking good… then this happened on several pieces after spray painting after the primer coat:

It appears the paint isn’t adhearing to the metal there, despite the fact that I washed these pieces in my dishwasher to clean them off, and sanded them to remove loose paint/scuff up the surface. Anyone know what I’m doing wrong? Maybe I didn’t clean the surface enough after sanding?

It seems the paint is going on better without a primer coat, as shown in this pic:

Only the upper wheel cover was primed, and it had 2 small spots that started cracking like above. I sanded those down to the metal, wiped it down with a damp cloth, and re-sprayed – which seems to be working. Hopefully another spray or two will even out the surface, as right now there’s a noticeable divit where I sanded down through the coats of paint.

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

10 comments so far

View 559dustdesigns's profile


633 posts in 3133 days

#1 posted 04-18-2010 06:33 AM

I like machine restorations. Keep at it, it’s looking great.

-- Aaron - central California "If you haven't got the time to do it right, when will you find the time to do it over?"

View davidroberts's profile


1027 posts in 3451 days

#2 posted 04-18-2010 07:24 AM

I just referred another LJer to

These guys spray paint old restoration project in their sleep. They will offer you some solid advice.

As for me, gives some causes for wrinkling, lifting or blistering:

Paint wrinkling is a severe puckering of the paint film that appears like the skin of a prune. It is more common
with enamel paints. There is a loss of gloss as paint dries.

Causes of Wrinkling Improper drying. When a freshly applied topcoat is baked or force dried too soon, softening of the undercoats can occur. This increases topcoat solvent penetration and swelling.In addition, baking or force drying causes surface layers to dry too soon. The combination of these forces causes wrinkling.
release their solvents and set up at the same rate as the surface layer, which results in wrinkling.
enamel can cause wrinkling.
shrink before sublayers have released their solvents. This results in abnormal surface drying and wrinkling
in uneven patterns.

Improper or rapid change in shop temperature. Drafts of warm air cause enamel top to “skin” or set up and

Preventing Wrinkling Allow proper drying time for undercoats and topcoats. When force drying alkyd enamel, baking additive is
required to retard surface setup until the lower layers harden. Lesser amounts can be used in hot weather.
Read and carefully follow product instructions.

Do not use too many topcoats. Allow sufficient flash and drying times. Select the proper reducer and avoid using incompatible materials such as a reducer with lacquer products or thinner with enamel products.

Schedule painting to avoid temperature extremes or rapid temperature changes.

-- Better woodworking through old hand tools.

View jerryz's profile


164 posts in 3244 days

#3 posted 04-18-2010 07:31 AM


Sometime oils will penetrate the metal surface and prevent the paint to stick, remember that all surfaces as solid as they look are none the less porous, if there was rust there, then that will also increase the porosity, making the absorbtion of an unwanted oil more likely.

Judicious cleaning and degreasing and sometimes sanding the surface will cure the troublesome spot.

Keep at it.

And have fun, the journey to get there is certainly something to enjoy as much as the end result.

View Jimi_C's profile


507 posts in 3200 days

#4 posted 04-18-2010 07:35 AM

Thanks, that’s very helpful. I think I’m guilty of laying it on too thick, so I’m trying to give short little sprays to prevent that from happening. I’m also going to try and allow more time to dry – I had given the primer about 12 hours to dry, but maybe that wasn’t enough considering cooler temperatures over night. I just started using my 500W halogens to try and help dry it quicker, so I don’t think drying it too quickly was the issue.

I’m going to let everything I’ve painted dry for a day, and continue using the halogens to help it cure. I just have to control my urge to get a perfect coat on the first time – multiple thin coats appears to be the way to go.

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

View marcb's profile


768 posts in 3639 days

#5 posted 04-18-2010 09:13 PM

Wash with mineral spirits then wash with acetone and wear nitrile gloves while doing it.

The wrinkling may have just been you put a 2nd coat on after the window for applying the 2nd coat. If you miss the short early window you have to wait until its fully cured to hit it again.

View Dennisgrosen's profile


10880 posts in 3080 days

#6 posted 04-18-2010 09:41 PM

I second marcb
you allso have to have 21degrees celcius (I don´t know what in farhenheit)
when you paint and during dryingtime


View Jimi_C's profile


507 posts in 3200 days

#7 posted 04-19-2010 01:07 AM

@marcb: I think you nailed it. I think I’m waiting too long, but then not long enough. I’ve been letting the paint dry for a few hours before doing another coat, not realizing that spray enamel has that short of a time between coatings. I’ll definitely do touch-ups much sooner from now on, and I won’t do anything else with the ones I’ve painted for a couple of days. I may even bake them at 100-150 for a little while to make sure they’re fully cured.

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

View Dark_Lightning's profile


3146 posts in 3074 days

#8 posted 04-19-2010 04:28 AM

I’ll bet the halogen lights are driving the finish to skin over, and the paint underneath is still wet. Getting the finish hot (especially on metal) can cause this. Just let it flash off normally. If this happened before you were using halogen lights, you’re putting on too much paint. I just finished a couple of totes for my boutique wood and the stains and finishes, and the first coat of Varathane (it’s leftovers that I’m using up) took 12 hours to dry. I normally use nitrocellulose lacquer. I have no wrinkle issues with that, I have more trouble staying ahead of the flash-to-dry while I’m brushing it on…so I usually spray it.

-- Random Orbital Nailer

View Jimi_C's profile


507 posts in 3200 days

#9 posted 04-19-2010 04:39 AM

Yeah it happened before I started using the halogens, so I believe it was a combo of using too much and then following it up with a top coat after too much time had passed (but before it had fully cured).

-- The difference between being defeated and admitting defeat is what makes all the difference in the world - Upton Sinclair, "The Jungle"

View marcb's profile


768 posts in 3639 days

#10 posted 04-20-2010 03:21 AM

I actually get the metal hot with halogens and hit it with Ace brand rattle cans. Never had a finish fail that way. 2 coats primer, 1 light coat spray followed by 1/2 the max wait time and 2 more thick coats at just within the wait window.

Then just set it aside for a week or more. Spray cans are thinned so bad they take forever to cure.

most of all just don’t get into a rush otherwise restoring becomes a chore and you don’t need another one of those.

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