Adjusted earnings of $0.87 per share in the fourth quarter equaled that of prior year.
In 2020, GAAP earnings were adjusted to exclude $6 million of expense or $0.28 per share and included a non-cash impairment of a small overseas investment.
2019 fourth quarter adjusted results excluded a net gain of $1.2 million or $0.05 per share, mostly related to a post retirement plan settlement.
In the fourth quarter, adjusted operating income of $21 million and corresponding earnings per share of $0.87 both equaled the prior year.
With the combination of a strong market demand, new product launches and efficient manufacturing, technical product sales increased an impressive 11% versus 2019 and adjusted operating income of $18 million reached the highest quarterly level in recent history.
Market demand in Fine Paper & Packaging, as expected, has a more extended recovery curve and we remain on track for this business to recover 90% of its pre-COVID quarterly run rate of $90 million this year.
We aggressively reduced costs and working capital, resulting in free cash flow of $75 million, one of our highest years ever.
Versus the third quarter sales increased 8%; adjusted operating income was up by more than 30%; and adjusted earnings per share jumped almost 60%.
These results were led by our Technical Products segment, which now makes up almost 65% of our total revenue.
Sales of $137 million in the quarter were up from quarter three, and more impressively, grew 11% versus last year.
The increase was driven primarily by volume growth and helped by currency translation as the stronger euro increased the top line by about $5 million.
Our filtration business has continued to perform extremely well and fourth quarter revenues were up almost 30% to a record $66 million.
Transportation, filtration media sales grew strongly in Europe and the U.S. and sales of industrial filters increased by more than 20%.
Quarterly revenues also included about $4 million for face mask media, which we began selling in 2020.
Outside of filtration, our Industrial Solutions business also performed well with almost 20% growth in backings, primarily due to increased tape revenue with new products introduced at some of our most strategic customers earlier in the year.
Segment adjusted operating income of $18 million was up from $10 million in the fourth quarter of 2019 and operating margins also increased from 8% to 13% of sales.
Turning to Fine Paper & Packaging, net sales of $70 million increase from the prior quarter and, as expected, due to COVID, were below sales in the fourth quarter of 2019.
Segment adjusted operating profit was just under $8 million, up 15% from the third quarter, but below prior year due to lower sales and production volumes and a less favorable mix.
Consolidated SG&A was $21.5 million, down almost $2 million from last year.
In 2021, with the resumption of more normalized spending, we expect quarterly SG&A of approximately $25 million with unallocated corporate costs of $5.5 million.
Interest expense was $3.1 million in the quarter, up from $2.8 million in 2019.
Our income tax rate in the fourth quarter was 15% compared to 19% in the prior year.
On an ongoing annual basis, we expect our tax rate to be approximately 22%.
With $37 million of cash on hand and no borrowings against our revolver, year-end liquidity was over $175 million and remains in excellent shape.
Cash generated from operations in the fourth quarter was $13 million, and while down from the fourth quarter of 2019, it decreased for the right reasons.
In addition, as noted in our last call, we accelerated $6 million of retirement plan cash contributions into 2020.
Fourth quarter capital spending was $7 million.
For the full year, capital spending was only $19 million as we cut or deferred non-critical items.
In 2021, we expect to resume more normal spending to around $35 million.
Input costs in 2021 could be more than $20 million higher than in 2020.
With the euro currently over $1.20, it's more than $0.05 above the 2020 average.
Each $0.05 is worth about $10 million to annually of sales and a little less than $2 million of operating income or $0.10 per share.
Publishing is a relatively small category with sales of less than $30 million and mid-single digit operating margins.
The Neenah Operating System will also be an important contributor with incremental value creation of over $20 million annually when fully implemented.

Summary:
Adjusted earnings of $0.87 per share in the fourth quarter equaled that of prior year.
In the fourth quarter, adjusted operating income of $21 million and corresponding earnings per share of $0.87 both equaled the prior year.